Lengthening Shims fit over the stripper screw threads and under the shoulder which, in effect, lengthens the stripper screw length. Made from a 302 full hard stainless steel. Fits six different shoulder screw sizes from 6mm to 20mm diameter. Precision Brand 330 Piece Metric Lengthening Shim contains 10 each of the following sizes in six thicknesses (0.125mm, 0.25mm, 0.40mm, 0.50mm, 0.65mm, and 0.80mm): 6mm I.D. x 8mm O.D.; 8mm I.D. x 10mm O.D.; 10mm I.D. x 12mm O.D.; 12mm I.D. x 16mm O.D.; and 16mm I.D. x 20mm O.D. And 5mm x 6mm in 0.125mm, 0.25mm, and 0.40mm.