This is the Highland Deluxe Inline Shut Off for Second Stage Features: Install between standard regulator hose and second stage Slide machined Delrin collar to shut off gas flow Commonly used with deco rigs, stage bottles & drysuit inflation Prevent critical gas loss 9/16-18 UNF male inlet to 9/16"-18 UNF female outlet threads Low pressure use only - below 200 psi Highland by XS Scuba&';s Deluxe Inline Shut-Off is an inline valve that can be used for closing off the air flow to your second stage regulator or inflator mechanism for a dry suit. Easy to install on standard hoses placed between the hose and the second stage regulator or between the first stage regulator and power inflator hose for quick and easy shut-off of air or to allow air flow to continue. Highly visible red colored visual indicator of closed position and green colored visual indicator of open position. "