Receive-your-calls-easily-with-your-Twiins-D1-hands-free-Very-easy-to-install-it-fits-in-most-helmet-models-and-it-is-fully-inte-grated-inside-the-helmet-Specifications-Connect-your-phone-and-receive-calls-using-only-one-button-Ready-to-connect-with-cellular-phones-and-smartphones-Blue-tooth-Compact-and-miniaturized-electronics-integrated-on-one-speaker-LED-red-blue-indicator-showing-the-state-of-functioning-integrated-on-the-microphone-Intercom-available-by-linking-with-a-Twiins-D3-or-D2-HSAi-Answer-your-calls-or-follow-GPS-instructions-Rechargeable-by-USB-Easy-to-install