The standard 4-inch AquaDuty 4400 submersible pump from Franklin Pump Systems features hydraulics designed to improve efficiency and minimize wear, even when pumping abrasives (sand). The ceramic shaft sleeve and rubber discharge bearing are intended to protect the shaft and eliminate sand wear. An intermediate bearing is said to provide improved shaft stability in all units greater than or equal to 2 HP, or longer than 24 inches in length. Other features include thermoplastic impellers and stages, and urethane eye and hub seals. Franklin Pump Systems, Card No. 223