Jack plates provide greater stability to bottle jacks and hydraulic rams; Lightweight and easy to handle; Each unit has non-skid surface to prevent jacks from sliding under wet or oily conditions; Complies with OSHA regulation 29 CFR 1926.305, “When it is necessary to provide a firm foundation, the base of the jack shall be blocked or cribbed."; Length: 12" (30.5 cm); Width: 12" (30.5 cm); Height: 1" (2.54 cm); Capacity: 50 tons; Weight: 5lbs.(2.3 kg)