Discontinued Silicone Sawblade O-Ring
1g, 0g, 00g/9mm, and 00g/10mm were produced by Kaos as 0g, 00g, 7/16", and 1/2", respectively, and have these sizes printed on them. Although silicone is stretchy and these o-rings will fit over their originally intended size plug, it causes the teeth of the sawblades to stretch in odd ways and lie flat against the wearable surface of the plug. The o-rings will fit best on the plugs that they are listed here as.
Jewelry is measured through a gauge system (see chart below). The higher the gauge number the smaller the wire is. A standard "earring" is usually 20 gauge. Jewelry gauges/sizes can vary between manufacturers. There is no universal regulation on companies to make a standard size in body jewelry. A big part of this is that some jewelry is made overseas and measured in millimeters. And in the USA jewelry is measured in inches/gauges. So many times jewelry can be anywhere from .5mm to 1mm different.