... as your design. 3.Various materials. 4.Good quality. quick coupling features:1.It can be used under a variety ... hold the mating part together.4.Before delivery,all the quick couplers and plugs will be strictly tested for its working ... pressure,air leakage,surface finishing and thread test.5.Common working ... /4″,1″,1 1/4″,1 1/2″,2″. Quick release coupling