Push button or remote start eith automatic reset for exact, fully automatic timing of all darkroom work. Interval and remaining time indicators. SAfelight goes out when button is operated. Luminous dial, linecord, enlarger, and safelight outlets are polarized with a two wire ground. Small receptacle accepts operation. Available in 4cycles. 60 second with 1 second calibration. 15 second with 1/4 calibrations. 3 minute with 3 second calibrations. 5 minute with 5 second calibrations.