The Zoo Med Repticare Terrarium Timer is a 24 hour programmable lighting timer designed for your terrarium lighting. It automatically controls a single lamp or other element by setting an on and off time at different points of the day. This timer allows you to regulate your terrarium's photoperiod with ease so that you can provide a natural day/night cycle for your reptiles. Equipped with a grounded 3-prong receptacle for safety, and a l arge analog dial for simple programing! 2.75" x 2.25" x 4.75"