Purchase a 1" PEX Barb x 1" FPT Adapter - Brass (524991)
WHK 10 PACK PEX Fittings 1/2 Inch X 1/2 Pex Drop Ear Elbow Female NTP Thread Adaptor,Use for Pex Pipe 1/2 Inch Fittings Connect and Fix Tub Spout,Shower Head (Brass) - Amazon.com
Apollo 1/2 in. Brass PEX-A Barb x 1/2 in. CPVC Straight Adapter EPXCPVC12 - The Home Depot
The Plumber's Choice 3/4 in. x 3/4 in. Brass PEX Barb x Female Pipe Thread Adapter Fitting (5-Pack) 34345EPFA - The Home Depot