This pack of 5 micro LED puck lights are small and convenient. Each light comes with an adhesive backing that will attach to most surfaces. Every light comes loaded with CR2032 batteries for use right out of the package. The base screws off making the batteries replaceable for multiple uses. These lights are o-ring sealed with an IPX6 waterproof rating. Take them camping, stow them in a cooler or tackle box, and never worry about them getting wet. They have an impressive run time of up to 10 hours.