I have 3 G4's. Two from a powerset and one individual. I linked up all 3 on the intercom but the first one I tried to use in the middle and linking up to both channel A and B at the same time did not work. I tried to do the same with one of the other two and it worked. I did not read the manuals all that closely and I believe there are two different manuals, one for the powerset and one for the individual units. The VOX feature was turned on and I didn't think to turn it off so I had two constantly open channels as both other units were on bikes without windshields and the road and wind noise kept the VOX opened all the time. Other than the price, which I believe makes the product over rated, and the inability to use ear buds instead of their little speakers (which must be right up against your ear) and the claim of up to 1 mile range (it's false advertising clear and simple-bluetooth was never intended nor designed to get that kind of range and even if they have documented proof that you can reach a mile, it's under the best most optimum conditions. They really should advertise it's "solid" for maybe a quarter mile at best and spotty further out. A realistic evaluation of it's range with the regular disclaimers you see about terrain having an effect.) So that's why I say it's over rated. The other features are great. I have all 3 fitted to a half helmet so I don't know why another post said it could not be done. I am intertested in anyone coming up with a modification for ear buds in place tof the speakers but it must be understood the longer speaker wire also acts as the FM antenna. So if an earbud mod was installed, that one speaker wire should still remain. Does anyone know if when the rechargable batteries no longer hold a charge the company will replace them? or sell new batteries and let us install them ourselves?