These pin backs locking clasps are made of nickel-plated copper, which are durable and sturdy. They can lock your pins firmly to keep them secure. The pin back locking is easy on-off action, spring loaded fastener simply need you to push to lock them, then push on the base to secure them ,finally pull to loosen the lock and remove it.

Specifications: 
Dimensions: 0.39in / 1 cm in diameter / 0.24in / 0.6 cm in height