PSI Audio AVAA C20 Black, Active Bass Absorber, Absorbs room modes between 15 and 150 Hz, Reverberation time is significantly reduced in this frequency range, Effectiveness corresponds to an absorber of 25 times the size, No calibration or adjustment to the room is required, Mobile and flexible solution, Dimensions (W x H x D): 424 x 509 x 300 mm, Weight: 13 kg, Colour: Black