James explains the finer details of MC4’s the differences between 4mm, 6mm & 10mm.
What is the difference between 4, 6, & 10mm MC4s?
There is a couple of subtle differences. The first is that the grommet within the actual housing; on the 4 and 6mm, you can see there is a smaller grommet and on the 10mm there is a larger grommet, for obviously accepting the larger cables.
There is also a very slight but important difference with the pins. The pins on the 10mm have larger side tabs to accommodate the copper and the cable going into them and a larger opening where you put your cable in as well.