Oring used with Air Check - New Style used from about 1993 to present.
Used on late model Autotrol 155 and all 255 water softener valves.
NOTE: Air Check - New Style Kit 1032416 - AP1032416,
Comes with this Oring, so you don't need to order it separately.
Cross reference old PN # 40A220) = model Technetic 1000