car antenna

Does anyone know what those 2 big pucks are on the top of most of the explorers and some crown victorias? I suspect that they're PCTEL Trooper antennas or Motorola AN000163A01s but I'm unsure. If someone could please let me know, thank you.

Ok i have looked at tons of antennas and i am confused on a few different things for example a dual band and a tri band antenna if the tri band lets you cover more why would people even bother with a dual band is it because that if a antenna is programmed for a specific freqs it will pick up...