Sizes (Carabiner) Overall Length: 40mm (height) x 23mm (width) Inner Diameter: 8mm (height) x 16mm (width) Wire Diameter: Approximately 2mm (D-Ring) Inner Diameter: 20mm x 12mm The included backpack buckle is sized to be used in combination with the carabiner. It is sized to allow a 15mm wide strap to pass through. Since the carabiner and backpack buckle are a set, you can create an adjustable shoulder strap. I will be listing unused materials little by little (*´-`) I will be listing them at a lower price than when I purchased them, so please consider them☆ Bundle discounts are also available. Please feel free to contact me. Although it is a new, unused item, Please purchase it if you understand that it has been stored at home☆