Harris 601 C02 Regulator with 6mm barb is made specifically for use with aquariums or homebrew. This single-stage regulator is designed to be compact and economical, but with features typically available in more expensive regulators. It is used where weight, cost and size are factors. Harris 601 Regulator has dual metal case gauges and safety relief valve. With smooth adjustment, 6mm barbed hose fitting and special threads to reduce the risk of leaks, it is perfect for the home brewer. Made by Harris to ISO 9002