Product DetailsTitanium Internally Threaded Flat Back Stud - 18 Gauge Fancy CZ Opal Hypoallergenic Implant Grade Titanium Flat Back Earring. Get triple the style with this 18 gauge lip ring. It's made with a 6mm hypoallergenic ASTM F-136 implant grade titanium straight post with a flat disc end. It features a pair of oval clear gems flanking a matching white synthetic opal. It also features an internally threaded design for maximum comfort on insertion and removal. You can even rock this jewelry in multiple piercings including tragus, helix, ear lobe and some nostril piercings. With such a timeless style and such thoughtful details, this flat back earring is one you'll love three times as much.Specifications18 Gauge (1mm), 1/4" (6mm), ASTM F-136 Titanium Straight Post, Synthetic Opal, Internally Threaded Post, Externally Threaded Screw on Top