Keychain flashlight
The Olight i3E is not the smallest keychain light. That is still the Photon, powered by a watch battery. But the Olight i3E is the smallest brightest light that runs on an easily available battery: the AAA. It’s the size of your pinky: 2 inches/6 cm long, and costs $10. One AAA will power it for years of occasional use, for when you need light more focused than a phone’s. (And I use a rechargeable AAA.) — KK