Squeeze both ends of the back at the same time and it opens up to allow insertion onto the post 925 STERLING SILVER: Non-irritating for sensitive ears, hypoallergenic, keep durable and shinning forever. 2 PAIRS ROSE GOLD EARRING BACKS: The package includes 2 pairs of earring backs: about 0.24 inch 6mm long, 0.28 inch 7mm wide, 0.06 inch 1.5mm thick, hole: 0.05 inch 1.2mm . Fit Post Size From 0.03 to 0.04 , unusable for Screwback or Plain Post. LOCKING DESIGN: These 925 locking earrings backs has a built-in spring to hold your precious earrings firmly and firmly. Use these 925 sterling silver to lock the back of the earrings to protect the earrings you like and never worry about losing them. EXQUISITE PLASTIC BOX: Comes with a small plastic box: about 68 x 52 x 11mm, easy storage of accessories and not easy to lose. EASY TO USE: Squeeze both ends of the back at the same time and it opens up to allow insertion onto the post. To take the earrings off, simply squeeze the ends again and pull it over the post, and it will come off immediately.