All the DIN-to-Yoke valve insert adapters for valves sold by Dive Gear Express use two #112 DIN O-rings, the same size as commonly found in DIN regulators. Regardless, if the adapter remains permanently in the valve, the rear O-ring rarely if ever needs replacing and only the face O-ring where the yoke regulator attaches needs to be changed. While the standard O-ring in yoke valves is a #014, the slightly 'fatter' #112 actually seals better and is less likely to extrude. For more information, see our O-rings page