Alternative Units for Purchase & Sales

Alternative Units for Purchase & Sales

Hi,

We need to be able to use alternative Units for items. 

Use Case:
We buy Cat-6 Networking Cables in "Rolls" of 305 mtr or 100 mtr, which are Industry standard across all manufacturers. However, when we do Projects, our Clients expect us to Invoice them in "Meters".

Is there a way where we can create a Complex Unit of Measurement, where we say "Roll of 305 mtr".  Now, I can Purchase in Rolls, but Sell in Meters.

Please advise.

KB