The GrovTec 1/2X28 Thread Protector features one-piece steel construction with a durable Black Oxide finish designed specifically for AR barrel protection.GrovTec Thread Protector Model GTHM2451/2 X 28 threading for standard AR barrelsOne-piece steel construction for maximum durabilityBlack Oxide finish for corrosion resistance0.705" outer diameter 0.637" lengthEssential for protecting threaded AR barrel ends from damage and debris when muzzle devices are not installed ensuring clean threads for future accessories.