Hello Biker ́s in many posts stands what a helmet fits well and which one is preferred. Sometimes I see bikers with microphone !? Does that work at all? I have a Bluetooth headset, and a cheap HJC helmet (yes ashes on my head) but I don ́t understand a word from the Navi. Are there really helmets that I still understand the Navi? How about the traffic safety, because of the insulation and Martinshorn? Don ́t tear me apart because of the helmet, lg Roland