The Sentinel MDT-1 Master Digital Timer is recycling timer that combines the 2 main timing functions plus overheating protection into one unit. First it has a timer for your lights that you can program for any light cycle you want. The MDT-1 further protects your lamps by having a hot start delay. This means the Sentinel MDT-1 will not allow for the bulb to be "re-struck" or turned back on before the user selectable delay period is over. Re-striking a hot bulb is bad for it...dont do it! The MDT-1 has a second "recycle timer" built in. This timer can be configured down to the second (not minute like others) level. In addition to the tiers the MDT-1 Master Digital Timer will shut down the power if you room gets above the set point. This is good protection in the event a fan or ducting failure. The MDT-1 is cheap insurance for your garden. If you grow indoors you need a Sentinel MDT-1 period. Specifications: * One timer for your lights * One cycle timer (day, night or 24-hour) * Overheat protection (shuts down lights) * Power: 15 amps @ 120 volts * Accurate clock +/- 12 seconds/year