Ballast tank drain pump, 1100 GPH. Used as fill on some models, see more pictures for more details. PLEASE NOTE!! The manufacturer has changed this pump. See more images for details, the newer pump should fit, and provide better service. NOTE: Depending on the location of the pump you may have to make some modifications. Please check out the post on Planet Nautique where one customer does a great job describing this issue; CLICK HERE.