? This series of couplers and connectors is designed to interchange with the industrial interchange series of other manufacturers ? A drag guard protects the sliding sleeve from being snagged or uncoupled ? Six stainless steel locking balls provide greater surface contact with the connector for a more balanced & secure connection ? Type 15 Series Coilhose Couplers will accept all 15 Series Coilhose Connectors ? Type 58 and 12 Series Coilhose Couplers are automatic for applications where a simple "one-handed" push-to-connect operation is desirable ? All 1/4 body couplers are brass, all 3/8 & 1/2 body couplers are zinc chromate plated steel