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:11, Page:037
Big Book Catalog, Issue:69, Page:036
Sinclair, Issue:5B, Page:252
SPECS: High-density, thermo-plastic rubber, ½"