Quality Material: Upgraded locking pin backs are made of quality nickel-plated copper, durable and sturdy, unique snap design, locks your needle securely, keep them secure will not fall off or get lost. Easy to Use: No tools required, spring loaded latch design for easier locking and removal, just push the base to lock and secure them, pull to release the lock and remove it. change your pins whenever you want. Widely Used: The metal pin backs are suitable for pins, lapel pin, name tags, display books, lanyards, bags, vests, hats, jean button, badge, enamel pin and DIY crafts etc. Best Choic: 30PCS pin back locks with clear storage case packed, more convenient storage, The size of the pins back is 0.4inch diameter, 0.25inch height, small and easy to use. better meet the decorating needs of you and your family.