Tail pieces are threaded with NPS (straight) female pipe threads, and are for use with Groco SV Series seacocks, or any product with straight male pipe threads. The use of these tail pieces on tapered (NPT) pipe thread is acceptable only for low pressure applications, and then only with generous use of pipe sealant or thread tape.

Unlike tapered pipe threads which seal by exerting pressure on the threads themselves, straight threaded pipe fittings effect sealing by the compression of a soft material onto the external thread, or with the use of a flat gasket - as used with garden hose.