For Chainmaille: Works most often with 18g 3/16" jump rings or similar sized rings. This size is thick and durable. It works very well in European, Persian & Japanese weaves. This is a great all around size for chainmaille. You can do a lot of projects.
For leather: Works well with 5mm leather cord or to hold together 2 strands of 2mm leather cord.
Other uses: This size works very well as a bead spacer to protect delicate beads that are strung such as lampwork beads. They can also act as a buffer to hold beads in place in wireworking. Orings are used as stitch markers for Knitting & Crochet and can also be used for Macrame and Seed Bead Crafts. EPDM Orings were developed to form a waterproof seal. They can be used with LED lights to form a waterproof seal between the bulb and hardware. These have also been used for body piercings that often require a stopper of this sort, tattoo equipment,paint guns, bicycle & Industrial parts.
Sizing:The ID or Inner Diameter is the size of the hole. Generally, choose an inner diamter slightly smaller than you require. The rubber will stretch to fit over items and form a strong seal or hold items in place.
The below table shows the AR average of a jump ring combined with this O-Ring size
