Any good piece of wire that is used to connect things. I use #14 stranded wire. It's a good balance of size vs. current cap. It only needs to be a few inches long if just connecting the fixed inputs. Other wire will work (#16 for ex.). Don't use too small # wire or it will limit the power to the inputs.
Higher the wire # = the thinner or smaller dia. it is. That means it can't carry as much amps.
