A shim is a washer or thin strip of material used to align parts, make them fit, or reduce wear. Shims may also be used as spacers to fill gaps between parts subject to wear. On machinery installations pumps, motors, etc. the recommended practice requires new shims to be placed under every supporting foot. Specifications. Size 0.024 in.. Height 0.65 in.. Width 3 in.. Length 2.2 in.