This listing is for a single ASTM F136 implant grade titanium push-pin flat back stud. Post measures 1/4" (6mm) in length. 18 GA. The post base is 3mm. If you would like to swap for a 4mm width base, please let us know before your order is shipped!Colors available: 18K Gold Plated Titanium, Titanium*Please see site return policy for more information regarding flat back studs!