If you are looking for a high-performance antenna and allowing you to increase the signal range for cheap, this is for you. You can put the antenna you want after this little USB adapter (small is relative, it is rather very big compared to the competition).
By cons, for BackTrack (5 at the time), compatibility concerns, some advanced features not working, and therefore it is better to turn to an Alfa Network AWUS036H, the reference in the field (you can find it on Amazon if required)