Type schematic (not to scale) of a MIG nozzle, labelled with the printed size and nozzle mount cited in the specifications below; this part's outside diameter, bore and length are not in our sources.
Bernard N2C12 MIG nozzle
Bernard N2C12 Nozzle 1/2", Copper, Slip-On: size 1/2 in, material Copper, nozzle mount Slip-On.