50 Pairs(50 Pins + 50 Backs) Stainless Steel Stud Earrings Metal Flathead Posts Pin Backs Blank Plug 4 Mm. Wholesale Lots Craft DIY Accessories and Supply Made of high quality stainless steel. 50 Pairs(50 pins + 50 backs). The pin length of approximately 11 mm., head pin has a diameter of approximately 6 mm. The head has a diameter of approximately 5 mm. DIY accessories and supply.