Will a 16340 make my CR123A light brighter?Updated 22 days ago

This depends on the specific flashlight. Some Fenix flashlights are designed to be compatible with both CR123A and 16340 batteries, while older or specific models are not - always check your flashlight's user manual before trying a 16340 in a light designed for CR123A. A 16340 is a different battery type than CR123A: despite being the same size and shape, they're as different as AA is from AAA. 16340 batteries are more powerful, so using one in a device not designed for it could work fine, work poorly, or in the worst case damage the electronics.