We had this installed for a client and all the work was done by the company, not only did it not function as promised it priced many items below cost. When we complained we were told that we did not understand the extension and we could not have our money back. Very bad experience all round, we cannot recommend this in any way and in our opinion it should be avoided at all costs. They simply did not seem to understand Amazon shipping in the USA, if it was a flat rate or a percentage for shipping then maybe it would have worked.
Maybe try it out but don't give them any money until you are 100% sure it works. Left with a very bad taste in our mouth.