Timeguard Compact Electronic Immersion Heater Timeswitch is ideal for controlling domestic immersion heaters and general purpose halogen, incandescent, CFL and fluorescent lighting loads. Rated at 16A the NTT03 timeswitch has a 720 hour rechargeable memory back up and offers comprehensive 24 hour/7 day control. The unit has four on and 4 off easy-set programme periods per day, 28 on and 28 off programmes per week. This compact timeswitch features large easy-push buttons and a wide variety of programming options, enabling you to get the most out of your water heater. It will fit a standard flush or surface mount box (32mm minimum depth).