This flow control washer is specifically designed for Fleck 5600SXT control valves and fits within the brine line assembly to meter the flow of saturated brine solution during the softener regeneration cycle. The 0.125 GPM flow rate is calibrated for standard residential and light commercial water softening applications. Proper flow control ensures complete ion exchange resin regeneration while preventing brine waste. This component is essential for maintaining accurate salt dosing and efficient softener operation. Replacement is typically needed when regeneration times become inconsistent or when brine draw is insufficient.