This should come standards with all miter saws in my opinion.  The stops are much more substantial that the stock photos suggest.  The are made out of 1/8" steel and are VERY sturdy.  They do somewhat interfere with the locking screws for my dw715 on the table extensions though.  I use a miter stand so it does not affect my usage.  Also come with nut backing plates for saws without tapped holes on the sides.  Highly recommend to anyone doing crown.