Nitecore’s T4K Keychain Flashlight Is a 4000-Lumen Pocket Powerhouse

If you want an outstanding light that won’t take up too much space in your bug-out bag and can offer some serious lightweight lumens, then the T4K is where it’s at. For us, this model reinforces Nitecore’s commitment to building quality lighting products.

Key Features
  • 4000 lumen max output
  • Multi-functional OLED display
  • Ultra-compact form factor
  • Concealed cooling design
  • Mechanical quick-release
  • Two lockout modes
  • Advanced power cut-off technology
  • Deep carry pocket clip
  • Demo and Daily modes
  • Five brightness levels
  • Advanced temperature regulation
  • Brand: Nitecore
  • Battery: Li-ion rechargeable (USB-C)
  • Retention: Keyring, pocket clip
  • Dimensions: 3.2 (l) x 1.2 (w) x 1.2 (h) inches (82.4 x 29.2 x 29.2 mm)
  • Max beam distance: ~686 feet (209 meters)
  • Max output: 4000 Lumens (turbo mode)
  • Max beam intensity: 10900 cd
  • Weight: 2.72 oz (77g)
  • LEDs: 4 x Cree XP-L2 V6
  • Max runtime: 67.0 hours (2.79 days)
  • Extremely bright
  • Can be used for self-defense
  • Exceptional runtime
  • Can clip to a baseball cap
  • Lockout mode prevents unwanted operation
  • Quick release makes everyday cary optional
  • Turbo mode only lasts a short time
  • Bulkier than other options
  • Lens prone to scratches when clipped
  • Pricey for a keychain flashlight
  • Will not tail stand
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Nitecore T4K other

In the world of flashlights, Nitecore is a well-respected manufacturer of technologically advanced handhelds. Nightcore flashlights are trusted by law enforcement, military members, hunters, preppers, and EDC enthusiasts.

The new Nitecore T4K keychain flashlight is targeted primarily at the latter two of those groups. And while this $89 compact keychain flashlight may look small, it packs a stunning 4000-lumen punch of brightness into its thumb-sized frame.

But is this light right for your bug-out bag? We’re going to help you figure that out.

Why Consider a Mini Keychain Flashlight?

First off, let’s get something out of the way: carrying a flashlight is almost always a good idea. Doing so enables you to see dropped items in a dark car, gives you a little needed light when poking around in a backpack or purse, and even allows you extra visibility when walking outside at night.

Keychain flashlights are perfect for these purposes because of their compact form factor.

However, the problem with most keychain lights is that they tend to rely on replaceable coin batteries, which means that they’re almost always out of power just when you need them most. That’s not the case with the T4K.

Nitecore’s Best Flashlight for EDC

What is most striking about this light is its rectangular shape. Where most pocket flashlights are more round, this one embraces its corners.

Like the previous EDC-favorite, the 1000 lumen Nitecore TUP, the T4K offers a lot of light in a petite package. The light has two buttons—one to change modes and one to power the light on and off—an OLED screen, a rechargeable 1000 mAh Li-ion battery, five modes, an IP54 rating, and four Cree XP-L2 LEDs.

It’s also got a detachable keyring and a pocket clip, so you can hook it to your keys or slide it into your jeans or backpack, depending on your preferences.

As an everyday carry light, the T4K is an absolute monster. It’s brighter than the TUP and yet just as easy to carry for most people.

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What’s in the Box?Everything in the Nitecore T4K box

  • The T4K Flashlight
  • A USB-C to USB-A Cable
  • A lobster claw keyring
  • Instruction manual and a few promotional inserts

Pocketable Design and Tactical Build Quality

The body of this light is mostly aluminum. That means Nitecore designed the T4K for decently rugged use. As a result, the construction feels solid, and viciously shaking the light doesn’t reveal any internal rattles. Around the perimeter are four hex screws that hold the light together.

The weight of the unit is 77g or around 2.71 ounces. Weighing less than three AA batteries, this device is highly portable.

At the business end of the T4k are the four Cree XP-L2 LEDs stacked in a two-by-two grid. Cree LEDs are some of the most popular in the pocket flashlight industry because they provide high-performance and substantial light output.

Rather than a standard reflector, the T4K uses total internal reflection or TIR lenses. TIR setups allow for more control over lighting output as light from the emitter is much more focused than what you get with a standard reflector.

A tiny OLED display on the unit’s face shows lumen values, mode setting, and time until the battery needs a top-up. This useful little screen takes the guesswork out of which mode you’re using. Additionally, having at-a-glance info on charge is helpful to avoid unexpected dead batteries.

Below the screen are two buttons that will allow you to turn on the light, change brightness, and invoke Turbo and Lockout modes. The stacked orientation of these buttons also ensures you won’t get them confused—even in the dark.

Under the logo on the front of the light is a naked USB-C port used for charging. One thing to point out here is the fact that there isn't a cover over this port. That's a bit concerning due to the potential for water penetration.

On the bottom of the T4K is a keyring attachment with a single button. Pressing this button allows the user to remove and reattach the light from their keys quickly. This entire mechanism is sturdy and can handle up to 30 kg of weight before it breaks. To me, I feel like you’d bend your keyring well before the metal D-ring attachment point fails.

On the rear of the unit is a broad metal pocket clip. This clip is strong, though it does feel as though you could bend it if you pulled too hard on the light body. This clip is also perfect for attaching to the brim of a baseball cap.

The tiny screws attaching the clip make it simple to remove and bend back into shape if it gets bent. Additionally, if you carry something like a Victorinox Rambler or a MiniChamp, the Philips screwdriver of those pocket tools fits these screws perfectly.

The T4K also has a one-meter impact resistance, and its IP54 rating keeps it working through sudden sprinkler splashes and downpour conditions.

I found that the build quality of this unit is top tier. It’s tough enough to throw into my bag or keep in my jeans next to my trusty Benchmade 940.

The only concern I have here is that the lens faces upward when clipped into your pocket. While that may not be an issue for some, if you have keys or coins smacking into the lens, you’re going to scratch it.

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Brightness on a Budget

The key feature of the $89 T4K is the 4000-lumen Turbo mode, which blasts a cornea-sizzling charge of white light into whichever direction the T4K is pointing. That means this light can be used to temporarily blind would-be attackers and other malcontents in an emergency.

The maximum intensity here is 10900 candelas, with a maximum throw distance for the light of 209 meters—or about 685 feet. That means this flashlight can help you see dark areas around two football fields away.

Turbo Mode

Four thousand lumens in a flashlight this small is pretty insane. I already own several EDC flashlights, including Maratac AAs and AAAs, ReyLight Pineapples, an Olight i3T and Olight i5T, and even a 2800-lumen Anduril-powered Lumintop FW3T. The latter of which was my brightest EDC flashlight—until the T4K came along.

This unit is ridiculously bright when in Turbo mode, and it’s not surprising that Nitecore included a warning in its documentation about shining this light into someone’s eyes.

Like many high-powered lights, accessing the Turbo mode will cause the T4K to heat up rapidly, so the use of this mode is limited. In addition, while engaged, you must hold the mode button, meaning you can’t just turn on Turbo mode and walk away.

While that may initially seem like a bad thing, trust me, it’s not. Without this feature, you could seriously burn yourself if this light was left on accidentally.

Once Turbo is engaged, a progress bar-type countdown appears on the screen. When the progress bar is empty, the light will automatically step down to the 200-lumen mode.

Built into the T4K is Nitecore’s proprietary Advanced Temperature Regulation, which regulates the output of the light based on ambient temperature conditions. So, if someone were to activate the Turbo mode, run out the timer, and then try to start Turbo again immediately, the light will sense the heat and adjust the timer accordingly.

I found that the timer reduced by around half when using Turbo in rapid succession.

Image Gallery (4 Images)

Additional Brightness Modes

Aside from the Turbo mode, the T4K also offers four additional modes: high, mid, low, and ultralow. These modes output 200, 65, 15, and one lumen(s), respectively.

Nightcore has reduced beam distance significantly in these modes. For example, on high, throw distance is 45 meters, and on ultralow, the distance drops to three meters.

All modes use a non-PWM (pulse width modulation), constant current circuit, so the beam stays steady. Overall, this type of beam is less strobe-like and easier on the eyes.

As for all modes, I found the Turbo to be pretty impressive. While the additional light modes are excellent for daily applications, the real reason this light is desirable is the high 4000-lumen output.

On-Board OLED

The bright white characters on the T4K’s OLED screen are easy to see, and they offer information about charge time, battery life, lumen output, and even time until the battery is discharged.

I found that the display is a valuable element for monitoring charge levels and determining runtime. However, the single-color screen is not overly impressive as OLEDs go. It displays the information that you need when you need it. Aside from that, the OLED doesn’t seem to be anything special.

Rechargeable Battery Life

Battery performance is crucial when it comes to pocket flashlights. If your battery is dead, then your flashlight is useless. That’s why Nitecore has made it easy to see battery levels with only a single button press.

Pushing the mode selection button brings up a battery level meter that tops out around 4.2v, which is the Li-ion standard for max charge. Nitecore has also built over-charge protection into the T4K, as well as over-discharge protection.

Since Li-ion cells are finicky, charge levels are important. With many of my other Li-ion cell flashlights, paying attention to charge levels is the only way to avoid damaging batteries. But Nitecore makes it easy to just plug your light in and forget about it when it needs charging.

There are no voltage meters or battery protection circuit chargers needed. Just plug your USB-C cable into a power outlet and come back in an hour or so.

As for longevity, on high, the T4K lasts a whopping two hours and 45 minutes before needing a top-up. In mid mode, you’ll get seven hours of life. Low brings that total up to 21 hours, and on ultralow, you’ll get almost three days (67 hours) of run time before the battery runs flat.

For my use, I found leaving the light set on high made the batteries last for about a week of occasional use. Like many others, I don’t use my pocket flashlight constantly; usually, it’s on only for a few minutes at a time. With this type of EDC use, you can get quite a bit of runtime out of the T4K before needing to recharge.

The only drawback here is that this battery is not replaceable. That means when it’s depleted, you’ll need to buy a new light.

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Memory and Lockout

Two additional features of this light are the lockout modes and the memory mode.

Memory Mode

One annoying thing about many pocket lights (coughMarataccough) is the lack of memory function. As a result, every time you want to use many lights, you have to cycle through the low, medium, and high modes to find the one you need.

The T4K, on the other hand, has built-in memory. So if you set it on high, then every time you turn the light on after that, the high setting will be the default.

As someone who uses high mode most of the time, I appreciate not having to cycle through every time I turn the flashlight on.


With a flashlight that's this bright, accidental button presses can be dangerous, especially if the light is in your pocket. To combat this, Nitecore has included two lockout modes that disable the face buttons until you unlock the unit.

The power button is disabled in lockout mode one, though you can still activate Turbo mode by holding the mode button down. In mode two, neither of the buttons will turn the T4K on until you unlock it.

It’s best to keep this on lockout mode two when you have this flashlight in your pocket, as it will prevent accidentally activating Turbo mode. If you still need access to Turbo quickly, then mode one will be the better choice, however.

Warranty and Repairability

Based on the 24-month warranty, Nitecore seems to have a lot of faith in this unit. Given the company’s reputation and the build quality of this light, I understand why it carries the warranty that it does.

Repairing the product, however, isn’t something that Nitecore is keen on. In fact, the product manual advises against opening this unit up as it will void the warranty.

What Shines About the Nitecore T4K

The small form factor, incredible Turbo brightness level, rugged construction, excellent warranty, and detachable keyring are all exceptional features of this pocket flashlight.

It’s excellent for EDCers, preppers, and even those folks who need a spare flashlight around their house or in their automobile. It feels nice in hand, the buttons are satisfyingly clicky, and the pocket clip is a wonderful addition.

For $89, this keychain flashlight is an exceptional value. Whether you need a good pocket light for walking the dog, or you just want some extra illumination for emergencies, I think you’ll be pleased with this offering. I know I am.

For me, the T4K has become my new bike bag flashlight, and I may even pick up a second one for the bug-out bag in my front closet.

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What Could Nitecore Improve?

The way I see it, there are only two main gripes I have with this light. The first is that it will not tail stand. Even if you remove the keyring, you won’t be able to balance this light on a flat surface. I tried on both my countertops and my wooden dining table. Neither attempt was successful.

If you are looking for a flashlight and tail standing is essential to you, then you’ll want to find another device that fits your application a bit better.

My second gripe is that the T4K was slightly too bulky for practical pocket carry. Its square shape also made it sit awkwardly when clipped inside my jeans.

I could see attaching this unit to a belt or keeping it in a purse. But stuffed in a pocket, it’s not going to work for me. As I’ve said before, I’m not a big guy, so this limitation might not affect everyone.

Additionally, despite the clip on the light being a “deep-carry” clip, about a quarter-inch of the device sticks up when using the pocket clip. That means there’s a quarter-inch that can bang against countertops or other hazards.

And, since the lens is part of this quarter-inch protrusion, I feel like it might get scratched after a few weeks of daily use. A slightly recessed lens might mitigate some of these scratches and add a bit of buffer for front impacts.

Lastly, I should probably mention that this light isn’t designed to attach to a Pic rail. So for that application, you should stick with something like the Olight Odin Mini or the Olight Baldr Pro.

These are all minor issues, however, and should not dissuade you from buying this excellent flashlight.

Our Verdict: Should You Buy the Nitecore T4K?

If you want an outstanding light that won’t take up too much space in your bug-out bag and can offer some serious lightweight lumens, then the T4K is where it’s at. For us, this model reinforces Nitecore’s commitment to building quality lighting products.

Overall, with the T4K, Nitecore has created one hell of a keychain flashlight. It absolutely shines in the areas of toughness, reliability, and performance, with very few downsides. Those qualities make buying the T4K a seriously bright idea.