The piston seal type Aston Seals KPD is composed of a dynamic seal element which assures exceptional high sealing performance. Two compact and small seal edges ensure perfect fluid control and concentrate the load against the dynamic surface. The cavity between the two external seal edges keeps a small quantity of fluid which reduces friction and wear. Side grooves ensure that pressure loads the energizing O-Ring in all work conditions - A standard size O-Ring with low permanent deformation as energizing component on the static side.