Fleck Part #61956-01. Replacement piston, seal, and spacer kit. Fits Fleck 5810SXT and 5810XTR2 downflow softeners. Replacement piston, seal, and spacer kit for Fleck 5810 series downflow softener valves. The downflow softener valve is the most common. Over time these parts can wear, allowing water to flow to the drain during normal operation. Replacing these part will stop most leaks down the drain.