Active bookshelf speaker system with 42W total power output, Supports Bluetooth, Optical, Coaxial and Dual RCA inputs, Bass, treble and master volume dials located on the side panel, Wireless remote control for volume adjustment and mute, Calibrated, flared front-facing bass reflect port, 100% MDF wooden enclosures to minimize acoustic resonance.Power output : L/R: 21W+21W RMS Signal to noise ratio : _85dBA (A) Noise level 25db Input sensitivity : LINE IN1: R/L:450±50mV LINE IN2: R/L:550±50mV OPT/COA: R/L:500±50mFFS Bluetooth: R/L:700±50mFFS Frequency response : 55Hz-20KHz Bass unit : 4 inch (116mm) Tweeter unit : _13mm silk dome tweeter