The BOSE's FREESPACE 3 II acoustimass module, a high-performance, low-frequency loudspeaker designed for small- to medium-sized installed applications. Without perceptible distortion, this public address system module provides deep, non-localized bass support down to 40 Hz. The Acoustimass bass module, when combined with the separately marketed FreeSpace 3 flush-mount satellite loudspeaker, creates a full-range system that may be deployed in two or four satellites per subwoofer. Surface-mount speakers can be mixed and matched to fit your room's style and layout.