Duo includes accessories for two helmets. All you need to navigate your way and get things done. With the latest Bluetooth technology on board, FREECOM 1+ is the indispensable single rider/rider communication system that includes all the essentials. Cutting-edge design: Only 16mm top-to-bottom. FREECOM 1+ aerodynamic design and low wind noise makes the other Bluetooth headsets look like blunt tools. Universal Connectivity: Connects to any other Bluetooth headset of any brand. Multi Featured: Automatic Volume Control, Mobile Conferencing, Charge while riding, Music & Radio Sharing, GPS, Music streaming, 2-Way Intercom, Connectivitywith two Bluetooth mobile devices, connects and pairs to any Bluetooth headset, Music Sharing, Hybrid Mic, FM radio, full phone connectivity, VOX, Cardo Connect App (iOS/Android), and on, and on, and on... Killer App: The Cardo Connect app is the perfect companion to your FREECOM 1+. Designed to work together it will make controlling, setting and using your unit easy and intuitive. Waterproof: No matter what you throw at it, your IP67 waterproof FREECOM 1+ will take the beating and keep you connected. High-quality Sound: Thin 40mm speakers and advanced sound processor, delivers optimal audio to size ratio.