Paid much more at a national boating supply chain but very happy with the results.  My 2004 27-foot Cruiser has black side panels.  I've never been able to remove all the oxidation until now.  I used a double sided wool buffing pad and a variable speed rotary buffer.  I wiped a fair amount of compound onto a 2' x 2' area with a hand applicator, then machine buffed at no more than 2000 rpm using medium pressure. After a few swipes back and forth, up and down, the compound started breaking down.  I then upped the buffer speed to 4000 rpm and lightly swiped back and forth until most of the compound turned to dust.  Toweled off, it left a brilliant shine and mirror finish.  I finished up with Collinite Fleet Wax.  For the first time since acquiring it in 2010, my boat looked like brand new.