This is an important upgrade Pack for first version of Galaxy Trucker. If you have the 1st version you should have this compatibility pack to play with Galaxy Trucker: The Big Expansion. It's not absolutely necessary, but the expansion uses slightly different backs for the ship tiles, which means they can be told apart from the first version of the base game.
Moreover, and more important, the cards are of a different size.
This compatibility Pack is free. You need only pay shipping cost.