little wheels with sinks...

Ok guys, you know the drill.....open the sink box, grab the sink out, keep chuck the drain cups in the cab for the plumber......whats left......

Sometimes, some krazy glue (which I give to the wife to fix toys with), sometimes putty, that you trash right away.....and (http://maplered.com) then the clips....

Every sink has a different selection, and (http://maplered.com) screws.....but the one thing I could never figure out.......What the hell are the little plastic pieces (that look like 3/4" tires) are for? Anyone?
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First party installer of 3cm Granite (http://tanbrown.org) in SW Ontario