Our Threadless Flat Backs are made with ASTM F136 implant-grade titanium. Made for the most sensitive ears, hypoallergenic and waterproof. Push pin style stud backs are inserted through the back of the ear, the top is tension set into place from the front with a slightly bent pin. See instruction photo for details.• 18k gold PVD plating• 5mm, 6mm or 8mm post length• 18 gauge post thickness, 3mm round back• Star measures 3mm24/7 day and night wear, no poke comfort and comfortable to sleep in with any piercing location. Insertion tool not necessary but available here.* Sold per earring (individually)