The 1/2" PEX-B × Polybutylene Coupling is a high-quality transition fitting designed to connect PEX-B tubing to existing polybutylene (PB) piping systems. Made from durable poly alloy, this coupling provides a secure, corrosion-resistant connection for residential plumbing retrofits and repairs. It is compatible with crimp or clamp ring systems and meets industry standards for potable water applications.