Feature These bulk pin backs are made of nickel-plated copper, durable and anti-rust. Smooth surface, sturdy and lock your pins firmly, without worrying they will fall off and provide you replacement to the torn screw or wrench locking mechanism; Keep your objects in place during important moments. Don"for t lose any of your pins, keep them secure by locking them in place with this handy set. Small screw pre set in for you. No more small parts to mess with. How to use: Put the black screw into the middle hole, then use a small wrench to screw half of the black screw to ensure that the fixed, fixed into the brooch or medal needs to be fixed to the other two ends of any small hole, then use a wrench to tighten the black screw gradually, to ensure that the fixed. Item Type :Pin Keepers Material:Brass Color:Silver, Type:A/B(Optional) Size: A Small 6x5mm B Large 6x9mm More detailed,please see photo. Quantity:10 Sets. Note: Size for manual measurement, there may be a 0 to 3mm error, belongs to the normal phenomenon. And due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you Package includes: 10 Sets x Pin Safe Locks.