Product review (4 stars): fridge is not yet a year old, shouldn't have had to replace it.
The Amazon 3rd party vendor was great.  The part is OEM, installed easily and works fine.  Make sure to take the clips off the old part when you install it.

BUT...the original shouldn't have broken...the fridge isn't even out of warranty and Whirlpool refused to honor the warranty because this rail is considered "cosmetic".  Will never buy a Whirlpool appliance again.