The PRO barrel line features extremely tight tolerances and are manufactured with pre-hardened chromium stainless steel (416R) that was originally designed for use in Match Grade rifle barrels. This material provides high tensile strength and toughness to withstand typical chamber pressures while still being highly corrosion resistant.ZEV PRO barrel bores are some of the most precise in the industry. Every barrel is double honed (rough and finish) until a minimum surface finish of 16 RA is reached. During this process the barrels are held to a final dimension of +/- 0.003" for consistency and accuracy.The barrels are cut rifled and 100% inspected for groove dimensions and broach finish. Available standard and threaded with 1/2 x 28 suppressor threading. Match Grade drop in barrel 1-10" twist rate SAAMI spec. Match chambersSPECSCaliber9mmMaterial416R StainlessFinishBlack DLCTwist Rate1-10"Tolerance+/- 0.003" DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.