A long long time ago when I first bought my (then new) Quicke loader and bale grab, both valves on the loader were male connections, with females on the implement hoses. Each pair had one red and one blue plastic cap and ring to help connecting up the same way each time. I've just bought two other bale grabs, one of which is new, with two females, the other second hand, with two males (neither with any coloured caps or telltales). A neighbour tells me that he has always had one male and one female on the loader, and again on the implement, so that it becomes second nature as to which way to open/close the grab. Not a huge issue, but is there an accepted convention ?