100 Pairs(100 Pins + 100 Backs) Clear Plastic Stud Earrings Posts Pin Backs Blank Plug 4 Mm. Wholesale Lots Craft DIY Accessories and Supply Made of high quality plastic, Ideal for those allergic to iron or stainless steel. 100 Pairs(100 pins + 100 backs). The pin length of approximately 4 mm., head pin has a diameter of approximately 1.3 mm. The head length of approximately 1.8 mm.,The head has a diameter of approximately 1.3 mm. Ideal for those allergic to iron or stainless steel and DIY accessories and supply.