A RaceTrack driver is a stadium-shaped transducer with different width and height ratios that offer a different distribution of speaker cone surface area. Their performance rivals that of more cumbersome circular drivers, offering optimized performance and more portability. This design allows for a slim cabinet with the full impact of a conventional subwoofer without the bulky size. The L1 Pro8 and L1 Pro16 have built-in subwoofers with RaceTrack drivers while the L1 Pro32 combines with either the Bose Sub1 or Sub2 powered bass module, which also feature slim RaceTrack drivers.