Front Sprocket - What is this?

Changing chain and sprockets today, for the first time.

Came across a difference in the old and new front sprockets. Old one (on the right) has a rubber ring around it that seems to be molded to it. New one, as you can see, does not have one.

Is it required? If so, does the old one come off, and is reusable?

Any help would be greatly appreciated.

The rubber dampens the noise of the chain on the sprocket. You'll notice the difference with the new (naked) one. No big deal, not required, just that the original is quieter. And costs more.

Thank You for the quick response.

Looks like I'll be riding tomorrow!