the 320 series coupling is an easy to use heavy duty coupling with long service life, it is a one hand operated safety coupling that releases pressure before disconnecting, eliminating the risk of hose kickback, the male threads on the coupling and nipple are provided with a thread seal at the factory, the couplings have a smaller outer dimension than comparable designs and are also available as an aluminum design, the fully automatic sequence simplifies operation, the eSafe design complies with ISO standard 4414 and EN 983