Battery operation: Powered by two built-in CR2016 button batteries. They can each be removed for replacement and endure 12 hours of continuous use. 2 lighting methods: Press the button briefly to activate the instant light, and sliding the switch backwards activate continuous lighting to release the hand. Practical light: mainly used for detecting or verifying any fluorescent liquid, such as pet urine, , currency, driver's license, ID card, passport, etc. Reliable light source: Each mini UV flashlight comes with a small LED bulb, providing 10 brightness levels and a lifespan of 100000 hours. Enough to meet your typical needs. Portable design: 1.6 inch L x 0.87inch W, weighing 0.2 ounces. Conveniently connect the torch to the keychain using a detachable keyring and carry it with you.