A series of check valves mounted in plastic push-in fittings have been introduced by Industrial Specialties Mfg. Inc., of Englewood, Colo. Standard in gray acetal with optional polypropylene bodies, the check valves of ABS material with stainless steel ball and spring are NSF approved. Mounted internally into the push-in fittings, flow and check direction can be in either direction. Fittings are available as straights, elbows, tees, crosses and numerous combinations.