These mini ultraviolet black light keychain lights by Opticz are a great addition to any keychain. They are drop resistant, water resistant, and have a super bright UV LED that lasts about 100,000 hours. The light output of 12 lumens more than sufficiently lights up any small area. The battery (type CR2016) lasts on average 12-14 hours and can easily be changed as needed. The light itself only weighs 6 grams and is about the size of quarter adding virtually no bulk to your keychain. Yet it's incredibly well built, durable, and designed to withstand the rigors of daily use without breaking. These lights feature a user friendly shape that fits comfortably in the hand allowing extended use with no fatigue. Simply slide the toggle switch for steady on illuminated light without the need to constantly depress a button. Beyond a keychain you can attach these UV lights to a zipper, belt loop, backpack, fishing gear, hiking gear, or a kids jacket to name a few. Can also be used as a safety light, to read hidden messages in invisible UV ink or paint, great for glow parties, giveaways, promotional events, grab bags or just to have fun lighting up other blacklight responsive items. DirectGlow has a large selection of many other UV flashlight styles along with a great variety of glow in the dark and blacklight responsive items. Need invisible UV pens or inks to use with your UV keychain light? Visit our store right now to see our entire selection!