Brownells Round Replacement Pins Features The Brownells AR-15/M16/M4 Round Replacement Pins are made specifically to fit the Brownells AR-15/M4 Buttstock Tool restoring its function when the factory pin wears out or goes missing. At 0.124 inches in diameter the round pin is sized to engage castle nuts with a round hole pattern rather than the square-tooth style giving the tool broader compatibility across different receiver extensions. Stainless steel construction resists corrosion which matters for a small part that spends time in a toolbox or range bag. Because the pins are inexpensive and sold in multiples replacing a lost pin does not mean buying a whole new tool. Finished in Silver the pins are easy to spot among other small hardware in a parts bin or kit. This pack of three provides enough spares to keep the buttstock tool functional through years of use on AR-15 pattern rifles. Armorers who service multiple rifles benefit from keeping extras on hand rather than searching for a replacement mid-build. It is a small practical accessory that keeps an essential AR-15 tool in working order. Brownells AR-15/M4 Buttstock Tool Round Replacement Pins Specifications Brand: Brownells Color: Silver Material: Stainless Steel Diameter: 0.124 Count: 3 Compatible Hosts: AR-15 Available At: GrabAGun