One model installs or removes AR style 308 barrel extensions safely and easily without making a "wrench" from an old bolt head. Machined, hardened, steel engagement teeth fully engage locking lugs for precise fit; alignment sleeve holds wrench square with barrel, prevents slipping or damage. 7/8" hex drive gives plenty of leverage to get really tight extensions loose. Mfg: P&L Development SPECS: 8620 steel, blue. 2-7/8" (7.3cm) long. Heat treated to Rc 48-52.