Piston and Seals KIT FLECK 5810
; Upflow Softener Part # 61956-02
Note: if you need the "filter" version, that is part number 61956-03
Also the more common version is the "Downflow" PN 61956-01.
Link to Pentair Water Youtube video showing hold to Disassembly the Fleck 5800https://www.youtube.com/watch?v=N05HFrtop2Y