The Easy Change System changes your lift arms to a hook system, allowing you to hook your tractor to an implement without leaving your seat. No other quick hitch gives you this much flexibility for all of your implements. Fits Category 1 (up to 75 hp) and Category 2 Tractors (up to 150 hp) . Cat 2 size can be customized. Model: ECS-01 Pin Dia.: 7/8" (Lift Arm) Hook: 7/8" (Pin Dia. ofImplements) Model: ECS-02 Pin Dia.: 1 and 1/8"(lift Arm) Hook: 7/8"( Pin Dia. of Implements)