(2 Pack) Brass 1/2” PEX to 1/2” Hose Barb Connector Fitting, Lead-Free Adapter Heavy-Duty High-Pressure Support, Rust and Corrosion Resistant

Good old fashioned barbed fittings like this: If you need to transition from/to Pex from/to Flex hose use 1/2” PEX to 1/2” Hose Barb Connector You can use hose clamps, or surprisingly Pex B crimp bands work quite well as long as you use barb fittings (not Pex fittings). Flex hoses in RVs have a reputation of leaking, this is because RV manufactueres (ALL of them, even higher end like Brinkly) are lazy and use Pex fittings in flex hose when they should be using barb.