25mm x 31mm x 3mm O-Ring (5 pieces): Amazon.com: Industrial & Scientific
100pcs Round Flat Key Chain Rings, EEEkit 1inch/25mm Metal Split Ring Key Rings Chains, Metal Keychain Rings Split Ring for Home Car Keys Organization, Silver - Walmart.com
316 Stainless Steel Round Ring 25mm ID 4mm Thick 6 Pack - Walmart.com
Men's 10K Rose Gold Real Diamond Super Star Ring 10 CT 25MM
10-20 Pcs Rose Gold D Ring Buckles 25mm Belt Webbing Purse Bag Hardware Handbag D Rings Hardware Leather Craft D-ring - Buckles & Hooks - AliExpress