I have the HJC IS-MAX 2 Helmet and that Buyee BT unit, which is waterproof, fits the speaker inlay, like it was made for it. It came with multiple mounts for different helmets.
It also came with a rather large foam to cover the mike. I'm sure that's to cut down wind noise.
I had to remove it. My buddy was still able to hear me at 60+ MPH.
Pros: Inexpensive, great coverage, FM Radio, clear audio, compatible with other of BT units. Long battery life. Allows connection to Smart Phone, GPS, and Rider. Full music control from unit. Pair up to 3 riders, with any two communicating at one time.
*Great reviews, going by the amount of people that reviewed it.
Cons: A little tough to remove from helmet, (but I don't need it to be easily taken off anyway), I now charge it while on helmet.
*this is what got me..
I always take a stronger look at something that got 4 of 5 stars, but reviewed by 30 people, than something that got a 5 of 5 stars, but reviewed by 3