The Bose Virtually Invisible 191 speakers are a flush-mount, passive speaker solution designed for both in-wall and in-ceiling installations, connecting to your existing stereo or surround sound components. Their primary appeal is their ability to provide high-quality, room-filling sound coverage without the visual clutter of conventional speakers. This is achieved through the use of an Articulated Array speaker design with two precisely positioned 2.5-inch full-range drivers in each speaker. 

This design, combined with proprietary Stereo Everywhere technology, ensures a consistent and balanced stereo sound field over a wide listening area, eliminating the need for a single "sweet spot". The speakers feature a proprietary ported enclosure that ensures cleaner and deeper low-frequency performance, directing sound into the intended listening area and ensuring consistent performance regardless of the specific wall or ceiling cavity space. The units come with both rectangular and round paintable grilles, allowing them to match any room's decor. They are also magnetically shielded, allowing for safe placement near a television without causing interference.