Sometimes, when you’re on a weeks-long trip — the kind that requires a flashlight — you don’t want a device that needs to be topped up every few hours or so. And when it comes to battery, more is always better. That’s why when a flashlight claims it can run for the better part of two days, you just have to stop and look. That light is the Fenix PD36R Pro, from the brand that topped our ranking of the most popular flashlight brands, which we did because it produces almost everything — from tactical lights to campsite lanterns — and it does it well.

Here’s the deal with the battery. The PD36R PRO runs on a 5000mAh 21700 cell, which is significantly larger than the cell on the iPhone 17 Pro and is actually beefier than what you’ll find in many of the <a href="https://www.slashgear.com/1780275/best-pocket-flashlights-according-to-users/” target=”_blank”>best pocket flashlights you can buy. Keep it on the lowest Eco setting, and Fenix says you’ll be able to squeeze out up to 42 hours. That said, as soon as you ask for more light, the runtime starts dropping quickly. For instance, if you keep the light running at the 2800-lumen Turbo mode, Fenix says the runtime drops to about three and a half hours. But that’s a small cost to pay for a beam that reaches a whopping 1,247 feet, which is close to a quarter mile. If that feels too low, you also get a High setting, though Fenix rates it only about 25 minutes longer than Turbo. Once drained, it tops back up over USB-C, and a fully drained cell refills in about three hours.

To operate the PD36R PRO, you get just two buttons, both of which sit on its tail end. One handles power while the other cycles through the brightness modes. They’re ergonomically designed and are close enough that your thumb can work both without fumbling. Your gloves won’t be mixing them up either, since they’re shaped differently, too. You also get the option to clip on a remote switch and mount the whole thing to a weapon.

The body itself is made of machined aluminum with a hard-anodized coating, which should help it against drops. And while the official product page doesn’t mention an IP rating, Fenix does say it survives a two-meter dunk. As for total life, the Luminus SFT-70 LED inside is rated for 50,000 hours, so it’ll likely outlast your interest in owning a flashlight. The light also remembers the last brightness you picked, and there’s a strobe on tap.

Knives and Tools, which reviewed the light, did have one nitpick. The Eco mode, the same setting that gets you that glorious battery life, bottoms out at 30 lumens, which runs a touch bright if you just want to read in bed.

As for the company, Fenix has shipped to more than 100 countries since its start in the early 2000s. It’s a Chinese outfit based in Shenzhen with a US support arm in Colorado. The PRO sells for around $120 on Amazon. The box throws in a holster, lanyard, and charging cable, but you’ll need to bring your own wall plug. Right now, Fenix is also tossing in a free keychain light with the black model, a tidy little extra in the vein of the best and brightest keychain flashlights. It’s billed as a limited-time deal, though, so it may not stick around.