This kit contains 100 assorted size rivets housed in a handy plastic storage case. The set includes 25 pieces each of the following sizes: 3.2 x 6.3mm, 3.2 x 8mm, 3.2 x 10mm, and 3.2 x 16mm. These rivets are suitable for use with hand or air pop riveter guns. Amtech S5100.