The lightened piston PRO of TopMax Elaborazioni is made with a compound based on DELRIN, Elastomer and Fiberglass, fused and industrially molded in specific percentages provided by TopMax Elaborazioni. The rack of this type of PRO piston is made of metal powders in M.I.M. (Metal Injection Molding), with a value of about 98/99% of full on the total.