I made the mistake of buying the C4 helmet. It has speakers and mike built in, only needing to add the battery and communicator unit in order to have communication in the helmet (supposedly)
Good - very quiet.
Good - microphone is very selective, so having a phone call on the road the other party couldn't tell I was on my bike.
Bad - poor airflow in front of my face. I end up with the visor cracked open all the time. Might be good for winter, but def not summer.
Bad - The integrated Sena communicator - too tinny if no earplugs, too soft if wearing plugs. Also I have yet to successfully connect the system to any other headset, including trying with another C4 helmit.
Overall, with the poor air and the worse Sena, I would not recommend this to anyone.