1/4"-28 TPI, 0.306 to 0.326" OD, 0.375" L, 304 Stainless Steel, 8-1/4-Coils, Diamond Knurled, Free Running, Screw Threaded Insert T1191-4C375 Screw Threaded Insert Type Diamond Knurled, Free Running Nominal Diameter 1/4 Inch TPI 28 Thread Series UNF-2A...