A 4000-lumen light is blindingly bright. And this one fits in your pocket. Nitecore’s T4K flashlight is a quad core smart keychain light that throws a beam up to 600-feet to light up the darkest night. With 5 lighting modes, an OLED display shows battery life, user mode, & run-time while an integrated 1000mAh battery provides 67 hours of back-up life.