5600 Low Water Piston Assembly ( has Gray End Cap ) sometimes used on "city" water where no iron is present. Uses a shorter Backwash cycle. PN 60102-20
Low Water Piston cuts the Back Wash and Rapid Rinse ( second back wash ) cycle time to 7 minutes each. Standard softener piston ( 60102-00 ) is 10 minutes each. Filter Piston ( 60102-10 ) is 15 minutes each.