20 AWG = 0.5 mm2
18 AWG = 0.75 mm2
17 AWG = 1 mm2
16 AWG = 1.5 mm2
14 AWG = 2.5 mm2
12 AWG = 4.0 mm2
10 AWG = 6.0 mm2

I use 4.9mm2 (sold as 6mm OD, which is pretty meaningless) auto electrical cable, red and black in a black sheath. Its almost too big for the Axiom binding posts, and is too big for the Pioneer's binding posts, but I eventually got it all in there.

It's probably not Oxygen Free though *gasp*

I paid about $60AUD for a 30m (100ft) roll... so that monoprice is pretty damned good.