The Clack WS1 Interior Parts Kit includes all the main interior moving parts that come into contact with your hard untreated water. The kit includes the piston, spacer stack assembly and the regenerant piston.
Clack Ws1 Downflow Piston Part # V3011
Clack WS1 Spacer Stack Assembly Part # V3005
Clack WS1 Regenerant Piston Part # V3174