Want perfect stereo sound? These headphones are equipped with Bluetooth 4.1 + EDR APT-X audio decode technology and CVC 6.0 Noise Isolation Technology for clearer music and microphone sound and reduced outside noises. They feature ergonomic design and silicone ear hooks that secure behind your ears and rest comfortably in the ear canal. Three sizes (S/M/L) of custom comfortable silicone earbuds ensure a comfortable and secure fit for everyone and Advanced IPX7 nano-coating keeps the headphones protected against sweat and moisture. No wonder they’re bestsellers!