Large choc: NFPA standards require Wheel Chocs to be mounted on fire apparatus before bening placed in service per NFPA 1901-09. Zico Chocs feature high-ternsile strength aluminum construction, large rear opening hand grip, and double row of rugged teeth to grip almost any firm surface. WARNING: undersized chocs may fail to restrain vehicle . The vehicle may either roll over or crush an undersized choc, possibly resulting in bodily injury or property damage. The AC-2 is: 8-1/4" high, 8-5/8" Wide and 15" long. It weighs 7.4 pounds. Please see our QCH-2 for a horizontal choc holder or the QCH-22 for a vertical choc holder. Model QCH-SL Safety latch may be added to any ZICO horizontal choc holder.