c & phone functions. ? ? ? ? ?Surround type design is convenient to carry, more comfortable than other brands ? ?9mm high fidelity audio earplugs, life like clear sound ? ? ? ? ? ?Speaking key, Volum control keys, the music key. Up/down song keysBluetooth earphone with high quality sounds, steady signal over 10 meters, longer working time over 4hours.?Jianrong IC is top chipset in bluetooth headphone.Certificates: CE,ROHS,FC,ISOTransmission distance: 10mFrequency Response: 20Hz-20K