... voice transmission (3/4 helmet, mask opening), horn sound settings for 80-100 kilometers per hour listening.In 3, the existing ... , reduce the sealing-off of bad contact failure rate, increased battery capacity, from the original 200 Ma to 300 ma.Two ... , telephone, mobile phone to realize listen to music; wired wireless walkie-talkie, GPS, MP3 and other sound equipment, setting priorities, Bluetooth is ...