The HJC Smart 21B Bluetooth Communication Device is a 2nd Gen premium bluetooth intercom system that implements an all in one design that fully integrates into certain HJC helmets, allowing for reduces aerodynamic drag and overall weight hanging off the helmet, making a more comfortable ride for you!Features Bluetooth 5.1 connectivity and a 4-way intercom system.High Definition speakers allow for incredible sound range, boosting the mid to low pitched sounds.Audio multi tasking.Advanced noise canceling and countrol.Intercom range of 1,600m (1.6km).Suitable for HJC RPHA 2nd gen series - RPHA 31 / RPHA 71 / RPHA 91 and the HJC i71.The HJC Smart 21B Bluetooth Communication Device is a fantastic option if you have one of the compatible helmets. It features all of the tech of a high end intercom system yet takes up a lot less space. Being integrated into the helmet, the battery simply bolts on into the bottom of the back of the helmet and the wires are easily routed through dedicated channe