Package Contents: 30 pieces pin back locks with small clear storage case packed to avoid locking pin backs losing; each pin sizes is approx. 1 cm in diameter and 0.7 cm in height. Quality Material: pin backs are made of quality nickel-plated copper, small and sturdy; The metal material makes it durable and colorfast, giving you an incredibly sturdy and safe experience; The small size makes it unobtrusive while maintaining stability. Delicate Design: the pin backs match for most metal pin; Metal pin backs provides good grip of pin to keep it stay in place; Its firm and protective grip assures that you will never lose another pin. Easy Use: these pin keepers are easy to put on and take off without a tool; Simply push to secure onto pin post while holding onto your pin to release; These locking pin backs are very smooth and prevent the skin from getting stuck injury. Wide Applications: the metal pin back can be applied when tie tacks and lapel pins lose their back, or for homemade craft pins, suitable for brooches, name tags, display books, hanging ropes, bags, vests, hats, badges, collections, etc.