Thank you for your help,
But that I need is not just to record different unit of measure, I need to set a correspondence between two unit of measure. I mean if I have one barrel with 200L of capacity then I just have one item and base unit of measure it's "200L" and I have also "L" as unit of measure. If I got on hand one barrel, it mean I have 200L, then if I sell 50L, System should be able to give qty on hand 150L.