Lightweight & Portable: Small size, d weight of 1pc keychain light is 8g, easy 2 carry around. Has a 1" link chain. Easy to Use: Two modes 4 turning on d UV light, ON/OFF switch or squeeze button. Built-in Button Batteries: Powered by 2 * CR2016 lithium batteries, which was installed in d product. UV Checking: UV light can be used 4 detecting currency, passports, etc. It also can be used 2 test whether baby's diapers, clothes and other baby products contain fluorescent agents. Reg Price: TT$9.99