Amazon.com: Swpeet 60Pcs Heavy Duty 3/4 Inch - 20mm Gun-Black Multi-Purpose Metal O Ring Metal Rings for Hardware Bags Ring Hand DIY Accessories Keychains Belts and Dog Leas (Gun-Black, 3/4 Inch) :
EPDM O-Ring-2.5mm Wide 20mm ID - Pack of 50
O Ring Rubber, 20mm x 2mm, 03654627 pack of 10 - Elemental Microanalysis
12pcs High Quality 20mm Bronze O Rings Opening Keyring Spring - Etsy