These AR15 anti walk / anti rotation hammer and trigger pins are what you need to keep your receiver from excessive wear and tear. Keeping the hammer and trigger pins from rotating is especially important when shooting full auto or with pistol caliber builds, such as 9mm AR15's.
Standard .154" Pin Size (not for large pin Colts or M&P 22s
Comes with (2) Pins, (4) Screws, (2) wrenches & (1) guide cone