Cable boots finish and protect pass-through holes for wires and cables.
The cable boot snugs arpound the cables and is made soft, flexible vinyl.
The cable ring is rigid plastic and secures the boot to the mounting surface.
The boot and ring are a functional set, but are sold separately.
You must purchase one of each of the same size, unless you are just replacing one of them.

Rugged marine vinyl resists UV, gasoline and oil
A cable tie snugs the top of the boot around wires and cables