72 MHz is the "band" of frequencies used. The specific frequency, 72.330 MHz means 72,330,000 Hertz or in the old language, cycles per second. The transmitter and receiver must match for this to work.

And, to answer a previous question, these are crystals, not chips. And, they may or may not look alike, but that does not matter one bit. The outward appearance means absolutely nothing. It's what's inside of the "can" is what matters, and these "crystals" are "CUT" to a specific frequency.

The aircraft band has 50 channels, starting at 72.010 for channel 11 up to 72.990 for channel 60.

CGr.