Lately, 21700 flashlights are becoming more and more common and it’s not surprising to see why. 21700 batteries are extremely powerful, more powerful than an 18650 battery and just barely bigger. With this powerful lithium ion battery, you can get an impressive output or you can get impressive run times or both sometimes. I’ve reviewed a few 21700 flashlights and I have to admit that I’m really liking them. So I thought I would pick my five favorite 21700 flashlights and list them here. Let me know what you think.
Summary of Contents
Klarus XT21X 4000 Lumen Tactical Flashlight

First and foremost is my handy dandy Klarus XT21X 4000 lumen flashlight. You did not read that number wrong. This handheld flashlight delivers 4000 lumens of awesome power. It’s not just the power that makes this flashlight great for me, but the design and versatility as well.
With the Klarus XT21X, you have two tail switches and a side switch. You can operate the flashlight with either the tail switches or the side switch. It also features two programmable settings: the Tactical Setting and the Outdoor Setting. In the Tactical Setting, which is what I typically keep the light in, the tail switches give you a momentary on, an immediate turbo, and an immediate strobe. In the Outdoor Setting, the tail switches give you a momentary on, immediate turbo, and immediate low. However, the side switch also gives you an immediate low and a built in memory function, which is why I like keeping the flashlight in the Tactical Setting.
It’s a USB rechargeable flashlight which is always what I would prefer. It’s only compatible with 21700 batteries. So if you’re wanting any spare batteries, you have to get 21700s. This is the only downside to many 21700 flashlights. While 18650 flashlights can often run on two or three different battery types, many 21700 flashlights can only run on a 21700 battery. Nevertheless, this is such an extremely powerful and tactical flashlight that it’s definitely been one of my favorites. Check out the Klarus XT21X tactical flashlight.
Olight Seeker 2 Pro 3200 Lumen Flashlight
Another awesome 21700 flashlight is the Olight Seeker 2 Pro. If you’ve had an Olight before, you know it’s quality and durable and the Seeker 2 Pro is no different. It is a compact flashlight, almost an everyday carry light, but it doesn’t have a pocket clip which is a downside for sure. Still, the size of the light itself is great. It delivers 3200 lumens which is really powerful. But, it’s important to know that the turbo mode and high mode are both meant to be burst modes, meaning that they’re really not going to last for very long. So the 3200 lumens is going to step down to 600 lumens after a couple minutes. Also, the high brightness level of 1200 lumens is going to step down to 600 lumens in a couple minutes.
It’s easy to operate this light with a single side switch. It’s just a click for on and off and holding the button down to cycle through the brightness levels when the flashlight is on. It does have a memory function which is always convenient. You can also double click the side switch to go into an immediate turbo and triple click the side switch for the strobe mode. When the flash is off, you can hold down the side switch to get into the low mode. All excellent shortcuts.
It features a lockout mode for the side switch along with a timer function so the flashlight can turn off after 3 minutes or 9 minutes if you set the timer. This is a rather unique function. There’s also a really cool brightness level indicator and battery level indicator located right next to the side switch. So you can tell which brightness level you’re in and what your battery level is at.
The Seeker 2 Pro is a rechargeable flashlight and features a magnetic charging port located at the tail cap. So you can charge the Seeker 2 Pro with its included magnetic charging cable securely and easily. It only is compatible with the 21700 battery and it has a maximum runtime of 12 days or 288 hours. The Olight Seeker 2 Pro is a perfect flashlight for anyone on the job or general use. Make sure to check out the Olight Seeker 2 Pro flashlight.
Fenix PD36R 1600 Lumen Rechargeable Flashlight
Next up is the Fenix PD36R. This is another awesome compact flashlight and would definitely be great for EDC use. It does have a two-way pocket clip which really comes in handy. It delivers 1600 lumens and has a great balance between a spot and a dissipated spill.
You have the tail switch and side switch operation that is really easy to learn. The tail switch gives you the on and off along with the momentary on while the side switch cycles through the different outputs and gives you access to the strobe mode. The run times on the Fenix PD36R are really good. The 1600 lumens has a runtime of 2.9 hours which is really quite impressive. It has an ultra low at 30 lumens that runs at 115 hours as well and that’s a pretty decent run time.
It is only compatible with a 21700 battery. However, the Fenix PD36R is USB rechargeable and features USB type-c charging which I’d really like to see more often. So you do get a fast charge with this flashlight. With 21700 batteries, they can take a while to charge, so it’s really nice that this tactical flashlight features a USB type-c fast charging.
The PD36R is really great for general use, outdoor use, and even tactical use as it does have a momentary on along with a strobe. Make sure to check out the Fenix PD36R rechargeable flashlight.
Nitecore New P12 1200 Lumen Tactical Flashlight

This is a compact everyday carry flashlight that delivers 1200 lumens, a great amount of light. The New P12 may not be extremely powerful, but it makes up for it with its run times. If you’re looking for a flashlight that features long run times, you’ll definitely be interested in the New P12. In the high brightness mode of 1200 lumens, the runtime is 3 hours and 45 minutes. That is insane! And on the ultra low or moonlight mode of one lumen, the New P12 can last up to 1200 hours! This is an incredible amount of time! Nitecore really went all out to make a long running flashlight.
It’s operated using a tail switch and side switch where the tail switch turns on and off the flashlight and gives you a momentary on while the side switch cycles through the different brightness levels. It’s a standard user interface and doesn’t really require much learning to it. It does also feature two operation modes: The Tactical Mode and the Daily Mode. In the Tactical Mode, you’ll be able to access the four brightness levels and the strobe mode. In the Daily Mode, you’ll be able to access the four brightness levels and the three flashing modes which are strobe, SOS, and beacon.
The New P12 is not rechargeable, but it does come with a battery magazine so that you can equip the flashlight with either a single 18650 or two CR123 batteries. I think every 21700 flashlight should come with these magazines, especially if they’re not rechargeable. The New P12 is also compatible with multiple tactical accessories which is really convenient if you’re wanting to turn this flashlight into say a hunting flashlight. Make sure to check out the Nitecore New P12 tactical flashlight.
Fenix TK22 V2 1600 Lumen Tactical Flashlight

We’re onto our last flashlight for this list. Don’t think it makes it less great though! The Fenix TK22 V2 is a 1600 lumen flashlight that has a lot going for it. Not only is it powerful, this flashlight has a maximum beam distance of 405 meters so you can expect quite a focused beam with this light.
It features a standard tail switch and side switch operation which is a very simple user interface. With the tail switch, you can turn on and off the flashlight as well as access a momentary on. The side switch will allow you to cycle through the four brightness levels and access the strobe mode. It’s a great flashlight that you can just pick up, play around with for a few minutes, and know the user interface like the back of your hand.
The TK22 V2 is not rechargeable, but it does come with a battery holder so that way you can use an 18650 battery or a 21700 battery. I really appreciate the non-rechargeable 21700 flashlights that have battery holders and can take other types of batteries aside from 21700. This is a great tactical flashlight that Fenix recommends for law enforcement or tactical operations. So if you’re looking for a powerful tactical flashlight, check out the Fenix TK22 V2.
Final Thoughts
It is so wonderful to see so many brands come out with 21700 flashlights. This is an excellent battery due to its extremely high capacity and compact size. Most of these LED flashlights are barely bigger than an 18650 flashlight except for the XT21X which is pretty large and is probably the largest flashlight on this list. Nevertheless, you have five of the best tactical flashlights to choose from that take 21700 batteries. I’m excited to see more brands come out with 21700 flashlights.