A built-in timer turns the lights on at the same time every day and keeps them on for 6 hours. Only for indoor use. Built-in LED light source. LED life approx. 20,000 hours. Light color: warm white (2700 Kelvin). Only use batteries that are intended for the product. Do not mix old and new batteries, different brands or types. IKEA recommends LADDA rechargeable batteries. Batteries are sold separately; 3 pcs AA required. You can use them to decorate trees, frame windows, drape shelves, etc. The lighting chain is battery-operated so you can place it freely on your dinner table or around your home to give decorative points of light for parties or every day.