Enclosure: NEMA 1 rated indoor steel in gray finish. Spring hasp, with hole for lock, holds permanently attached, side hinged door closed. Three mounting holes on back plus box mounting holes. 7-3/4 in H x 5 in W x 3 in D. Switch rating: 10,000 W (40 amp) Max 250 volt, 60 Hz. Allows user to shift electricity use to "off-peak" time periods to save utility costs.