3.14 MR3 Three-unit moving iron music headphones, BA Balance Armature headphones, new style earbud stage monitor headphones,custom class public mode ER4 535 Driver: knowles moving iron unit: ED29689-(high frequency unit) +sonion unit 33AE001E-(composite mid and low frequency unit) , Housing: customized molds Cable Length: 130cm / main cable:85cm / splitter Y cable length:45cm Frequency Response:20HZ-20KHZ; Sensitivity:110db; Impendance:30ohm This earphone is made by a profession engineer who is an audiophile