L L Building WHT36 Whole House Fan TimersHighlights: 12 Hour Switch Box Standard Easily installed in standard 2 1 2"D vertically installed junction box Spring wound mechanical dial, open in the off position to permit fan operation from standard pull switch when not in use Operates with 1 HP motors and standard household current of 115 V, 60 Hz, single phase Includes durable plastic knob and wall plate marked in 2 hour increments Equipped with continuous on hold feature