Connecting 20mm UPV conduit: male or female adaptors?

Yes.

 

Whatever I happened to have with me!

 

A lot depends on the box, and how much space there is inside it.
I would usually use the female type as they take up less space inside the back box.
The male type are good if the 20mm hole is a bit big.

 

Female the majority of the time.

 

I agree with Dr Bodgit, I would not make a journey to the wholesalers just because I had the wrong gender adaptor. From the customer's pint of view their is no visible difference in the finished job. But from choice I prefer the bush and female fitting, it reminds me of how difficult it used to be installing steel conduit and how easy PVC is!

 

Female anyday - one bonus being that there is less risk of cable chaff