FanPod[TM] Auto uses innovative technology to switch the air freshener on or off with the flick of the restroom lights. When the light goes out, the built in sensor automatically turns the fan off. This saves battery life and moderates fragrance refill evaporation, thereby making it economical and more environmentally friendly. FanPod[TM] Programmable works with a built in timer that allows you to program it to run for 5 or 7 days each week. It turns the fan on or off according to your desired time and schedule. Switch it to run for 8 hours per day, 5 days per week, and the FanPod[TM] Programmable will allow the refill to last 60 days and will run up to 12 months with 2 alkaline batteries! Various fragrance refills available.