I have a Helix 10 G2N and my ducer went south. The best price I have found for the exact replacement is $305 There is another option at $190 but I loose the MEGA fetcher. What exactly does MEGA give me and is it worth the extra $$$ ?
Thanks,
JR

MEGA stands for MEGA HERTZ or 1000 KILO HERTZ. It's a frequency range just like 455 kHz or 800 kHz used with Humminbird Side Imaging and Down Imaging.
That higher frequency produces a thinner Imaging pulse than the lower frequencies and the thinner pulses produce sharper images.
Since newer units CHIRP the sonar frequencies, all three of those are CHIRPed. CHIRP broadcasts multiple frequencies per ping. The MEGA CHIRP's range is 1.0-1.3 MHz. Default is not the entire range, you will see the range displayed on the Imaging views that the unit is using.
The transducer does not produce the frequency, it is just a combo speaker/microphone that broadcasts the sound frequency and then detects the return sound frequency. The unit produces the frequencies, and the standard transducer for a unit is made to work best in those frequency ranges.

You can dumb down most units to function like an older model to use the older/cheaper/less capable transducers if you want.
If you state which one of the three different second generation Helix 10's with MEGA Imaging (the whole model name as shown in the SYSTEM STATUS view) you have and the model of the transducer you are considering, I can tell you what the possibilities are.