1/2"x 28 / 5/8"x 24 Thread Protector Standard Barrel Nut Thread Protector SteelFeatures Barrel thread protector is machined from steel to very high quality standards. Hardcoat anodized This thread protector works on most standard barrels and variants. Come with two sizes: 1 2" x 28 and 5 8" x 24 Specifications 1 2" x 28 Length: 0. 6" Outside Diameter: 0. 71" 5 8" x 24 Length: 0. 6" Outside Diameter: 0. 94" Color: Black Items Included One (1) 1 2"x28 5 8"x24 Barrel Thread Protector