This shows the pads, retaining clips and retaining pins for both upper and lower pistons. Also, the only other tool you need (just to make it easier) thin nosed pliers. But note the marks on the back of the pads made by the corresponding pistons - this is what the combination brake is all about. The smaller pistons (lower) are activated by the same hydraulic pressure in the line to the rear brake, their smaller diameter ensures the effective clamping force is much less .