You are looking at a brand new ten pack package of Line 20 Snaps 3/16" Post Black. The diameter of the cap and base is 1/2" or 13 mm. This item 1261-03 works well on leather thickness five to seven ounces. These snaps also come in brass and Nickel. These snaps are set with 8057-00 or 3630-00 which is also available in our stecksstore. Thank you for looking.