Stainless steel and threaded for either suppressor or compensator etc. I've shot about 400 rounds through this without a single failure and extremely accurate. Reason for sale: I bought this to shoot 9mm for practice, but I'd rather have a standard, non-threaded barrel--don't need the threaded barrel. Willing to trade for non-threaded G27 Storm Lake or LWD or will take $100 and you pay shipping (should be minimal). Pics available upon request. . .