When setting up a new item you want to carefully consider how you handle the units of measure and what units you need. When you setup an item you define the UOM for sales, purchase and inventory as the initial defaults. With unit conversations you can purchase and sell in any unit but you might want to consider you base unit for inventory and how you want to see on-hand.

Here is a quick overview.

AX2012 R3 CU9

Cheers

Lachlan