All sizes are displayed in their UK format. EU sizes may differ.\nHJC 50B Smart Motorcycle Helmet Bluetooth Intercom Communications Kit Black\nThe HJC 50B Smart motorcycle helmet Bluetooth kit is a 2nd generation premium Bluetooth communication system which has been co-developed with SENA and tailored specifically for HJC helmets. The motorbike Bluetooth kit provides an optimal environment with intuitive operations and easy installation. When riding you can listen to your music, GPS guide and also make phone calls through a Bluetooth connection.\nBased on the BT 5.0 low power system, the 50B (based on SENA 50S/50R) features both the MESH intercom and 4-way Bluetooth intercom features. The enhanced sound system properties include audio multi-tasking, sound equalizing, advanced noise-canceling, and more. The SMART HJC 2nd generation also comes equipped with HD speakers to enrich mid-to low-pitched sounds. All of this can be effortlessly controlled through the SMART HJC mobile app from .