For scope base adjustment, sight adjustment, head-space adjustment and checking, restoration of misaligned parts soldering on for buildup, inletting templates, spacers. You name it, and somewhere along the line a shim can be used for everything from shimming, to measuring, to fixing! KIT No. AC-24 consists of one piece, each, steel shim stock, 2A 1/2" x 6" in the following thicknesses: .001", .002", .003", .005", .010", .015". Mfg: Brownells