Gendax Bone Conduction Wireless Bluetooth 4.0 Headphones Anti Pollution Mask Handfree Headset with Built-in Microphone for Cycling Riding Driving Built-in Headphone and Free Your Hands: Wireless bone conduction headphone ensures handsfree calling / answering and music listening in driving,riding. Free Breath and Pure Filtration: Professional anti pollution mask makes you far-away from PM2.5 Less Interference and More Safety: Bone conduction speaker makes the sound directly transmitted to bone chain through internal conduction of bone, helps you enjoy the purest sound and keep sensitivity to surrounding sound in a noisy environment Scientific Design and Good Fitting: The three dimensional structure is designed precisely based on the data about facial structure in recent 20 years, repeat molding and correction help make it fitting to different facial shapes Clear Communication and Infinite Sharing: Built-in anti-interference microphone with sensitivity up to -4030DB, together with three-dimensional cutting of mask, reserves sufficient space for sound production, helps you communicate clearly without any obstacle