The TI-RANT 45 Piston is an ASAP piston and features heat-treated stainless steel construction. They have a bead-blasted matte finish and are engraved to identify the thread diameter, pitch, and direction of rotation for installation. This model is to fit the TI-RANT 45 suppressor onto a .40 caliber pistol with 9/16X24 tpi thread pattern.