Features a slightly crowned face to avoid damage to the skin. Dimension of the head is 3/4″. Overall length 3″. Compatible with .401″ shank rivet gun or hammer. For universal head and flush style rivets. .401 shank. Fits all .401 rivet guns. You must purchase a flush set and then the rivet set size you need. Each rivet set is 3-1/2″ long. Sizes 3/32″, 1/8″, 5/32″ and 3/16″ and 1/4″ straight.