1, Special designed Class D 4*50w Amplfier w/independent Bass &Treble control 2, 2 independent inputs, also can combined with audio in and out to one inputs 3 , 2 independent Zones,4Channels with its own Volume and bass and treble control 4, Can add WBR12 works as Wifi and bluetooth amplifier 5. Can add PB580 works as Bluetooth5.0 amplifiers 6. Can add it to AMP88 or AMP99, works as 6*50w Amplifiers, or add more as more channel amplifier as your request.