Burris Adaptor - Ruger to Weaver AdapterWith this adapter, you can use Burris Zee Rings on your Ruger rifle or handgun. It properly anchors and aligns your scope so you can consistently put rounds on the target. 2 piece, solid steel design Strong and lightweight Compatible with Ruger firearms that feature the proprietary Ruger integral mounting system (EXAMPLE of use: On picture: 2 Piece Base will fit the Ruger 77 17 & 77 22, the base at the back of the receiver clears the bolt OK and