With this Steel Riveting Block, there is no more guesswork on the length of wire to be cut. Use the holes at the top to pre-cut the perfect length of wire for your projects. The holes in the middle are about 1.8mm deep, thus every cut is just the right amount of wire needed to create "head" on both sides. The dimples on the left side are used for support when riveting in order to hold the shape of the rounded rivet head. The circles on the right side are for riveting eyelets in 3 different sizes without flattening the rounded rims. Dimples on the side of the block are for rivets and on the opposite side are circles for eyelets. Both of these sides are for CURVED surfaces and must be mounted in a vise.