The Sena pi turns your favorite outdoor-sport helmet into a Sena smart helmet with 2-way Bluetooth Intercom, no data plan or cell service required. This universal Bluetooth Intercom headset also serves as an audio output device, as it can pair to a smartphone so the user can listen to music, make or take phone calls, and listen to GPS navigation. Its compact design makes it easy to attach to most cycling or skating helmets, or any other helmet with a strap width of up to 18 mm (0.7 in).