Review on Mini Keychain Flashlight, Ultra-Small And Bright Key Ring Light Torch For EDC, Emergencies, Dog Walks, Reading And Sleeping - Perfect Gift For Students, Kids, And Parents (Red E1-ALU Alloy) by Nap Olivas

I haven't had it long enough to report on battery life. Seems well made and robust. Bright enough for finding dropped items, picking up after a dog, finding the key hole etc. It screws on and off but lacks a detent so it seems possible for it to unscrew too far and come apart in your pocket, but so far this has not happened. The batteries are changed by unscrewing it until the end comes off. It costs much more than the most common type of keychain lights but (1) it comes with three sets of batteries, (2) I think it's going to last much longer and (3) it's quite a bit brighter so I think it's a fair price for what you get.