I bought a Inova Microlight at Target for about $7. Uses two 2016 lithium batteries and is small enough to put on a keychain. It has high-beam, low-beam, strobe and signal settings. Seems plenty bright for just having one led bulb. So far it's mostly been used to guide me to the bathroom in the middle of the night. Come hunting season it'll be hanging from a lanyard around my neck.