I would say: just use them and don't worry about the gauge. If Kato thought they were robust enough, they will be fine.
If you really want to know, that info is often imprinted on the wire insulation. You might be able to find a piece which has that info. Or strip the insulation and measure the diameter of the wire. That is a bit difficult on stranded vs. soild wire, but it will give you a some idea of the gauge. There are lotos of wire gauge charts out in the Internet which specify the wire diameter.