The Exo Terra Dual Outlet Timer is ideal to automate the 24h daytime/nighttime cycle in your terrarium or to control on/off times of any terrarium plug-in device. Its 15 minute increments allow you to switch plug-in devices, like heat lamps, heat mats, hot rocks, rain pumps, etc, on/off periodically during 24 hours. Simply push down the segments according to the time you want the device to turn on and how long you wish for it to stay on. The Exo Terra Terrarium Timer features a manual override switch to bypass the timer function and supply power permanently.