Gates belts have a lifetime guarantee.
The HR has a self-adjusting mechanism so it is imperative that the correct length of belt is fitted.
I can't remember the exact length of belt, so best to go with genuine Nissan and once fitted the tension notches will fall into alignment.
However, you may have an underlying fault which has caused the belt to shred, so best to get this fixed first.
If you want to go Gates 2053, CMS have them in stock: http://www.clarkmotorsport.net/parts/Alternator-Drive-Belt/7PK2053