Quick connect o ring

I would suggest you to do some measurements if possible. The quick connectors I have are all from China and there are at two types. One type has the O ring pressing against the tip of the male connector while the other has the O ring going around the stem . The dimensions of the O rings are type dependent. If your connectors are from Foster, there is probably just one type. 
 
I would suggest you to do some measurements if possible. The quick connectors I have are all from China and there are at two types. One type has the O ring pressing against the tip of the male connector while the other has the O ring going around the stem . The dimensions of the O rings are type dependent. If your connectors are from Foster, there is probably just one type.

Yes MINE are the foster type, I bought a few foster o rings way back for my air tools. But wasn't sure if they would hold the fill pressure on my air rifles. They appear by the naked eye to be the 1/4x3/8x1/16.