Earring face : 8*8mm (conversion : 1 inch = 25.4mm or 1mm = 0.0393 inch)( Post Length 10mm / 3/8" One Size Fits All ) The back of this ear stud is Push Back with 925 Sterling Silver Post and Back Lightweight, easy to take in and out, yet stay securely in place And Comfy. Hypoallergenic, lead & nickel free Safe for sensitive ears. (comes with Sterling Silver Butterfly back , Extra Clear Silicone Bullet Clutch Ear Nuts for Earring Safety Backs and Little Plastic stored box.