Aero Precision APRH100367C: Features: Fits barrels with .936 OD Constructed from 4150 hardened steel Phosphate coating Low profile for easy fitment Set Screws are Steel 10-32 x 3/16 Knurled Cup Point Made in the USA *Roll pin not included* Please note: Aero Precision does not recommend the use of red thread locker on the threads of the set screws. If you decide to use thread locker Aero Precision recommends using the non permanent variety.