2-Post Rack-Mount Installation Kit for 3U Rack-Mount UPS Systems The RK2PC enables 2-post rack mounting of select Eaton UPS systems, including the 9PX5K, 9PX5KP1, 9PX5KP2, 9PX5KTF5, 9PX6K, 9PX6KG, 9PX6KP1, 9PX6KP2 and 9PX6KTF5, and extended battery and power modules.