The CST-1000 allows On times of 1000 minutes (16.66 hrs) and Off times of 1000 minutes. Often used to time lighting for cycles that do not necessarily correspond to normal 24 hour photoperiod cycles. For instance you might choose to run lights for 16 hrs on and then 6 hrs off and repeat this cycle. The CST-1000 operates on 110 VAC 15 Amp. and can be paired with the Green Air HAR1 for total control of day and night length of lighting cycles.