Completely self-contained string of tiny holiday lights has small white power unit with batteries installed. Add colorful accents to various items: Mini Christmas Trees, Elf on the Shelf, Reindeers, Doll Houses, Windows, Doors, or your Pet's Collar! Complete with batteries and ready to go - just pull out protective plastic film from power unit and turn slide switch "on". Control unit is only 2" x 0.9" x 0.25". Colorful 20 LED string is very bright and is 6.7ft long. Brand New!