Black rubber ring.  All rings are debossed with "22KILL" in red, except for the XS size, which is all black.

The rubber rings do not come in exact ring sizes, but each ring is flexible enough to fit about 2-3 different ring sizes.

XS: 60mm ~ 6.0 - 8.0
Sm: 65mm ~ 8.0 - 10.0
Med: 70mm ~ 10.0 - 13.0
Lrg: 75mm  ~ 13.0-16.0