The staggered diameters of the six pistons help eliminate tapered wear of the pads. More importantly, the pistons are made of stainless steel to reduce thermal transfer of heat into the brake fluid. They also feature dust and weather seals to hold up to road duty. The seals are recessed to ensure they never come in direct contact with the backing plate of the pad. This is critical since a seal that hits the red hot pad can cook and become the very debris that the seal is supposed to keep out.