The convention is SEMA (Specialty Equipment Manufacturers Association). Just under 100,000 people attend this auto-related show, and it usually takes up all of the Sands Convention center and more than 50% of the LV Convention center! I believe it's the 2nd or 3rd largest convention in Vegas (next to Comdex and maybe CES when it's held there).

To top it off, Comdex is the following weekend!