.25 Caliber (6,35mm) 416 Carpenter Technology "Project 70" Non-serial Numbered Stainless Steel, Swiss Screw Machined, Internally Threaded, Vacuum Deposition Coated Carbon Titanium Black Barrel With Integrated 180 Degree Flats (to Facilitate Installation and Removal). 6 Lands and Grooves. Right Hand Twist. Includes Industry Standard 1/2" - 28 Threaded Male Suppressor Adaptor and Diamond Knurled Cover. For Use With Any Psa-25, 1931 Fabrique Nationale "Baby Browning", Psp-25, Fraser or Bauer Pistol. Installation of the Threaded Barrel Might Require Minor Sanding and/or Polishing of the Slide Barrel Hole of the Pistol.