Invoice Fields

Hello,

Is it possible to show custome fields from the inventory
section on invoices?

For example, I have a custom field named "Size" for my
inventory, and I would also like this to appear on my
invoices.  Is there a way to do this?  I've been going
crazy the last couple of days trying to figure this out
but to no avail.

Thank you very much for any help.

- Paul