I defined a new unit of measure "pair" and I set it up bigger than the reference unit of measure by 2 under the uom category "Unit".

I created a new product and set its purchase uom to Pair and uom to Unit. If I receive the items in stock from a purchase order I am going to receive 2 and if I am going to buy an item I am going to buy 1. 

Is this the best approach to configure this uom? Or maybe should I create a new UOM called pair under a new uom category called Pair as well. and treat this item as a whole and not as seperate units?