The Tork A512H 12-Hour Spring-Wound In-Wall Twist Timer Is Designed to Control A Variety Of Indoor Appliances and Lights. Automate Your Home or Office to Save Energy and Money Using The Simple Twist Knob and Reliable Mechanical Timekeeping. Features A Time Range Of 30 Minutes to 12 Hours, Plus It Fits Into A Standard Electrical Box For In-Wall Mounting. Designed For Indoor Loads Such As Lights, Whole House Fans, Air Compressors, Water Heaters or Motors.