SpiroPure SP-PS-3921 is a compatible alternative pool and hot tub spa replacement for Watkins 78161 / 1642301-1, Filbur FC-3921, Unicel C-6350, and Pleatco PWK35B cartridges. SP-PS-3921 is designed to fit pools by Watkins Hot Spring Spas.

• Diameter: 6-3/8" (6.375")
• Length: 14"
• Top Hole: 2"
• Bottom Hole: 2"
• Top Style: Open
• Bottom Style: Open
• Media Area: 50 sqft
• Weight: 3 oz

• Darlly 67501
• Filbur FC-3921
• Pleatco PWK35B
• Pure N Clean PC-3921
• SD-01386
• Unicel C-6350
• Unicel C-6355
• Watkins Limelite 50
• Watkins 78161
• Watkins 1642301-1
• Watkins 78372
• 50 sq.ft. Hot Springs Spas/Watkins. Mfg.

• Watkins Hot Spring Spas