OPTI-MAX® Check Valve Cartridge Replacements, 1/8" Ball, Analytical (2pk), Stainless Steel Cartridge, Ceramic Ball & Seat
This cartridge also fits in all OPTI-MAX housings that will take 1/16" cartridges. Fits xx-56-xxxxx OPTI-MAX housings.
Cartridges are also available in other component combinations.