Transition from unthreaded to threaded pipe using the PVC 1 in. IPS UC X 1 in. IPS MPT Compression Adapter. This easy-fit adapter has one compression end that connects onto 1 in. IPS pipe end and one MPT end that threads into FPT pipe end. There's an adjustable nut on compression end of the adapter to tighten and secure it in place. The compression adapter provides a corrosion-free connection and reduces pull-out from pipes. Durable, leak-resistant compression adapter is made of PVC plastic. Gasket is made of santoprene.