Package Quantity: You'll get 16 pcs spring o rings, more than enough to use in a variety of lifestyle scenarios, such as dog tag clip, backpack accessories and more. Size: O Ring Inner Diameter: 3/8" (11mm), Outer diameter: 17.5mm, thick: 3.7 mm. Please understand, manual measurement may have ±1mm error. Versatile Clips: These 3/8" spring o ring can be used to small key clip, attach keyrings, or fasten tags and backpack zipper locks. Use your imagination and use the spring o ring where you wan. Material: The round carabiner is made of zinc alloy with a smooth surface that holds nothing securely in place without scratching or damaging the item. Spring o ring available as your DIY craft accessory. Spring Opening Design: The O-ring a spring-loaded design; simply press the spring mechanism on the O-ring to open and close it easily, allowing for installation and removal without tools. These versatile carabiner clips are perfect for keeping your keys, purse and more organized. Made of durable zinc alloy, each clip features spring opening that securely fastens items together without worry of them coming undone. Attach your pet's ID tag, house keys or key fob. They're great for clipping charms onto backpacks, belts or purse zipper pulls too. The Minimalist design won't burden the item, but it can't take too much weight either.