this may be a dumb question, but help

but i JUST got my suicidedoors.com diff bracket for my roadgrater on my sonoma. it has another ring with it (pictured below). I literally just opened the box, and haven't taken a look at my differential yet. what's it for? figured i'd ask before i screw something up swapping out brackets.

p.s. feel free to laugh at me when it's something simple

it goes between the diff cover and axle bracket to space it out so it wont smash the diff cover

ok, that's what i was thinking. but the ART bracket obviously didn't have that so i wanted to make sure. thanks bro.