The Vizio Wireless Subwoofer Replacement for VIZIO SB2021N H6 2.1 Channel Soundbar is a black, cube-shaped subwoofer that is compatible with the VIZIO SB2021N-H6 2.1-Channel Soundbar System. It features Bluetooth connectivity, Alexa smart home compatibility, and a 2000 mAh battery capacity. This subwoofer is designed to enhance the sound quality of your home audio system, providing a deeper bass experience for an immersive listening experience. Easy to set up and use, this Vizio subwoofer is a perfect addition to your home entertainment setup.