CCR divers use Swagelok QC6 connectors to plumb in offboard gas. The QC6 has sufficient flow for breathing gas, which is essential whenever a BOV is being used. We use genuine Swagelok 316 stainless with double shutoff service.
The entire back-end of the female QC6 is replaced rather than using adapters. This makes the female QC6 as short as possible.
Available in two thread sizes: 3/8″-24 male (typically used for MAVs or gas blocks) and 9/16″-18 male (connects to 2nd stage end of a LP hose).