These caliper pistons are a direct replacement for the original LD19, LD20 and LD65 pistons, but machined from type 304 stainless steel to minimize corrosion. Each is machined to a tolerance of 0.0002 inches and then polished to a sub-20 micron finish. In addition to corrosion resistance, stainless steel has excellent thermal insulation properties and will help keep the heat away from your brake fluid. Made in the USA. Sold individually.