Spacer shims are used with Compression Riveters to produce a precise rivet gap spacing. The correct gap spacing will produce consistent and uniform results. Conversly, an incorrectly gapped riveter will squeeze the rivet too much, or too little, resulting in poorly installed rivets. This kit contains 2 each of the following shim sizes: 1/64", 1/32", and 1/16". With it you will be able to make 1/64" adjustments in a range of 1/64" to 7/32". 1 lbs (0.5Kg) shipping weight.