For Chainmaille: Works most often with 20g 3/32", 7/64" & 1/8" jump rings . For its' size, this is a fairly thick O-Ring. Works great seed beaded Chainmaille because the holes are small and the seed beads can maintain their placement.
For leather: This size fits 2mm leather best but they can stretch for slightly larger thickness.
Other uses: These work really well as spacers to protect strung beads. EPDM O-Rings were developed to form a waterproof seal. These have also been used for body piercings that often require a stopper, machine & Industrial parts. O-Rings are also known as gaskets.
Sizing:The ID or Inner Diameter is the size of the hole. Generally, choose an inner diameter 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
