AUTOMATICALLY TURN LIGHTS ON AND OFF--- Automatically adjust the lighting in your aquarium to mimic your fish’s natural environment. For most aquariums, you can set the timer to 12 hours of light and 12 of darkness for a perfect balance. 24 HOUR TIMER--- The SunGrow analog timer has pins marking 15 minute increments over a 24 hour period. Create a daily and nightly schedule for your aquarium lights or heater and leave the timer to take care of everything. EASY TO PROGRAM--- The analog mechanical operation of this timer is simple to use. Push the pins up will switch your lights off, when you push the pins down the timer will switch on. SURGE PROTECTION--- This 24 hour timer switch is built with a grounded 3 prong receptacle for safety. This will protect any appliances you may be using in case of an electrical surge. MULTIPLE USES--- You can use this 2.08' W x 4.2' H timer switch for almost anything. Plug in aquarium lights, lamps, fans, household appliances or hydroponic systems for automated schedules.