For Use When Installation of Plastic Shims is Restricted by Building Codes Available in Three Thicknesses These CRL Aluminum Horseshoe Shims solve the problem on construction projects where the use of plastic horseshoe shims is restricted. They are fireproof to regulations and building codes, and are punched in the same 1/4, 1/8 and 1/16 inch (6.4, 3.2 and 1.6 millimeter) thicknesses as our plastic shims. Balanced for use in vertical and horizontal positions, but not color coded by size. Thickness: 1/8 in (3.2 mm) Length: 3 in (76 mm) Width: 2 in (51 mm) Minimum Order: 1 Box (100 Each).