R & S #237 same as OR4 and OR-38 with better RubberFDA standard for Water drinking / NSF 61 O-Ring for 10 inch Standard housings Same as Hydro Life 52530Pure Valve 5EZ50 and 4EZ50 Whirlpool: WHEJ1 Gold Central Water Filtration system 7170246 O-Ring Rain Soft Ultrafiner ll And UF Series Cap to Housing o-ring 12994 Home, Boat, Motor home Alternate Part Numbers, AP2077265, GN1515CBL, GXWH20F, Jandy Zodiac RO454100 O’Rings for LXi Pool & Spa heatersSears: STD302237, 42-34385Rain Soft 12994 Housing / Ultrefiner II and UF SeriesPelican PBB-OR410 Inch HousingsOriginal R&S ( all others are fake )Durometer 70A Fits Fleetwood Florpur Housing, Culligan RVF-10 Housing CCL-10-CLW Flow-Pur (POE12GHGACB) (Watts 520021 )Housing FH4200WW12 Size: ID 3 3/8 Make sure you have a standard housing Some specific Brands have their own size only Made In USA Complete Return Policy O-Ring problems: Send us your old O-Ring that worked and we will find you the proper O-Ring.