GPS Units - Weather Balloon
GPS Units are typically limited to controlled airspace (60kfeet, 18km), and 1000 knots.  These are commonly known as the COCOM limits.   For anything outside of that, you will probably have to go for a higher-end GPS unit and possibly some additional paperwork.

I believe that the uBlox module that is on that board implements the COCOM limits correctly.  In the uBlox G5010 datasheet, it gives the operational limits as 972 knots and 50km.

The DoD specification (I believe) says that a GPS unit should not operate above 60kfeet and 1000 or knots, but most of the manufacturers don't actually implement it this way.  The commonly cited list of high-altitude capable GPS receivers is here.

Some other companies produce GPS units to spec: most notably Inventek.