The SMART HJC 21B is the 2nd generation standard Bluetooth communication system, designed to seamlessly integrate with 21B-compatible HJC helmets by leveraging their structural attributes during installation. Based on Bluetooth 5.1 Low Power technology, the 21B offers a 4-way Bluetooth intercom function with a talk time of approximately 22 hours. The HD speakers provide enhanced sound quality, refining mid- to low-range tones. Key features include HD speakers, a range of 1600m, audio multitasking, universal intercom compatibility, and up to 22 hours of talk time. It is suitable for the following HJC helmets: RPHA 31, RPHA 71, RPHA 91, and i71.