A typical technical drawing of an oval head semi-tubular rivet Semi-tubular rivets (also known as tubular rivets) are similar to solid rivets, except they have a partial hole (opposite the head) at the tip. The purpose of this hole is to reduce the amount of force needed for application by https://redbottom.us/categories/regular/general/176-mastering-bag-making-a-guide-to-leathercrafts-hand-press-and-dies