The new Nihilo "Run Cool Brake Pistons" are designed to be stronger than stock and provide exceptional cooling performance with less brake drag. Most O.E.M. caliper pistons are made from aluminum that just cannot hold up to the heat and extreme demands of serious racing; when they get hot, the aluminum will distort, causing loss of hydraulic pressure and brake failure. Nihilo's Run Cool Pistons limit the area that boiling hot hydraulic fluid is able to come in contact with the piston leaving 2/3 of the piston volume in open air with breather holes to enhance the cooling ability. Cooler pistons improve piston retraction eliminating brake drag. The stock pistons are hollow and shaped like a cup - they hold the boiling hot brake fluid with no way of cooling them off, and this is why O.E.M. pistons warp and distort, causing all kinds of brake issues.