Instantly Tightens Loose Upper & Lower Receivers
Helps promote better accuracy by making the upper and lower
receiver fit tighter. Open upper receiver; drop this long-wearing,
rubber wedge into the rear of the lower, behind the push pin.
Absolutely no modifications required.
AR-15, Issue:09, Page:031
Big Book Catalog, Issue:66, Page:031
Law Enforcement / Police Store, Issue:09, Page:017
SPECS: High-density, thermo-plastic rubber, ½"