O-ring for Fleck 5600 & 9000 control valve that fits on the bottom of the control head and seats against the tank to create water-tight seal (Fleck part# 12281).Product FeaturesTank O-ringO-ring for Fleck 5600 & 9000 control valve that fits on the bottom of the control head and seats against the tank to create water-tight seal (Fleck part# 12281).Product DescriptionO-ring for Fleck 5600 & 9000 control valve that fits on the bottom of the control head and seats against the tank to create water-tight seal (Fleck part# 12281).More InfoO-ring for Fleck 5600 & 9000 control valve that fits on the bottom of the control head and seats against the tank to create water-tight seal (Fleck part# 12281).