Just curious if anyone knows the size of the tiny oring that is on the check valve in the bottom of those Chinese hand pumps? I am referring to the valve that keeps the pressurized air in the fill hose from finding its way back up in the pump. My calipers died so I can’t measure one at the current time. Thought maybe someone knows as I would like to order a bunch as this seems to be the one oring that fails on these pumps.