This item replaces the 'Fixed' D Ring on your rebreather harness to allow the D Ring to be 'movable' and repositioned on the harness as required.
You will need to unstitch the harness webbing to fit this item and restitch the webbing with the correct thread back into place. Please ask us if you require advice.
The D ring is used for attaching reels, spools, side mount pouch and light unit canisters etc.