This is a Wheeler Tool known as the Lapping Kit, model 1081035.
Aligning and lapping of new rings should become the standard practice whenever a scope is installed on a quality firearm. The alignment bars in this kit provide for perfect alignment of both rings and will also diagnose any misalignment problem" vertical or horizontal" giving you the opportunity to fix the problem before damaging the scope or experiencing frustration at the range.
Features:
Includes two 1 alignment bars, 1 lapping bar, lapping bar handle, and 220 grit lapping compound
Complete instructions included
