This durable Weaver 1-Piece.22 Tip-Off Adapter Base allows you to get the most out of your firearm. The base fits 3/8-inch grooved receivers. The adapter is made for non-factory dovetailed rifles and is constructed of the highest grade metal. This design promotes a sure, tight fit that gives maximum security. This will allow your scope to return to zero easier, even after long hours of use at the range. The stable construction provides you with a piece that will last a lifetime. Weaver TO-9, TO-10 & TO-11 bases accept either Detachable Top Mount Rings or Tip-Off Rings. Each have crossbolt slots and 3/8" grooves for both applications.