Q:

Lab power supply screw plug

I'm intending to buy a lab power supply, high likely a .. I'm thinking about a Korad KA3005D (see picture below). 
It does not come with cables for the Red + and Black - terminals, and I (also) would like to have a plug to use power not only via the (4mm) banana plugs, but also by screwing it to the same terminal. I'm intending to create a cable myself.
My questions:

For connecting the power cables it can be either connected to the banana plug or to the screw. On the cable, a half round iron 'circle' is needed … how is such half round thing called to connect to it? I mean the 'plug' that needs to be added to the Red + and Black - terminals.
What is the (inner) diameter (if it is standard)?

A:

It can have different names:

fork connector
Y (spade) connector
Y plug
(or any mix of keywords mentioned above)

The connectors have different inner diameters.
Either measure it when you have the power supply or estimate the diameter based on overall dimensions (it doesnt need to be that precise).

