Automatic Reverse-Flow Prevention Couplings Made of Brass Material Model AS-1, ... -1,2, OP-1,2 IMPA Code 850301-09 Automatic Reverse-Flow Prevention CouplingsFitted to the outlet pipe, connecting hose and ... .5 Female Thread850309OP-2PlugM16 x P1.5 Female Thread Automatic Reverse-Flow Prevention Couplings