Don't know the specs, but I do know they are not standard on my 2305... I went off to get a quick disconnect spare from the local princess-auto... they have 1/4, 3/8, etc... sizes.... I found one that was the right size end to fit into the quick disconnect, but the hose end thread was different.... All I can imagine is that they are metric... most (if not all) the hardware on the tractor is predominantly metric, so it could be the same with the couplers....