ChatterBox XBi2-H Wireless Intercom - -- Installs in specific HJC Helmet such as the IS-Max BT and CL-Max II Can do bike to bike intercom up to 1/4 of a mile between 3 bikes. (Requires 3 units) Stream music from a smartphone, or GPS. Perfect for a Zumo 550 or 660 6-8 hours of battery life per charge. Includes speakers, microphone, battery charger, bluetooth module.