The power/ground gauge numbers represents the main wire size of the amplifier kit.
Definitions are as follows:
Gauge (wire) - The diameter of a wire. The higher the number, the thinner the wire. Example: 4 gauge wire has more strands than 10 gauge wire.
AWG (American Wire Gauge) - A standard of the dimensional characteristics of wire used to conduct electrical current or signals. AWG is identical to the Brown and Sharpe (B & S) wire gauge.
Since 1857, The AWG (American Wire Gauge) system has been the standard for measuring the diameter of wire. AWG standard is the measure of bare wire to find true gauge. Companies that do not follow AWG Standards include the thickness of the wire jacket which means the actual wire is not "True to Gauge".
For the best performance from your amplifier wiring kit, make sure that the cable complies to the AWG standard.
The material that the wire is made of. Copper & aluminum are the most commonly used materials.
OFC - Oxygen Free Copper is the ideal choice for wire material. Copper is a superior electrical conductor, & does not expand or contract with heat.
CCA - Copper-Clad Aluminum is a suitable choice for lower powered or budget applications. The power transfer is not on par with OFC, but this material offers significant savings.