Product Details Hypoallergenic Flat Back Earring18 Gauge 5/16 Natural Green Onyx Oval Implant Grade Titanium Push In Threadless Stud Earring Simple style and striking colors mean this 18 gauge body jewelry is always in style. It's made with an 8mm ASTM F-136 implant grade titanium straight post with a flat disc back. It features a green natural onyx stone oval top that features a threadless design, for maximum comfort on insertion and removal and making it easy to change the end. Best of all, you can wear it in multiple piercings including earlobe, and nostril piercings. Classic jewelry and modern style make this elegant flat back earring a a winner.Specifications18 Gauge (1mm), 5/16" (8mm), ASTM F136 Implant Grade Titanium, Threadless, Push In, Flat Back, Natural Stone Green Onyx