We have John Guest 3/8" Faucet Connectors. 3/8" Faucet Connectors can hook directly to the faucet from the RO line. These connectors are for water systems and reverse osmosis systems only, not suitable for gas, compressed air, or vacuum applications. They use the John Guest push-fit technology, which makes connecting easy and simple. You can quickly connect and disconnect without tools. They're made with a food grade EPDM O-ring.