Bose Flush Mount Virtually Invisible 191 Speakers Tech 17/02/2014 Audio The Bose Flush mount Virtually Invisible 191 Speakers, feature two 2.5″ (6.4 cm) full-range drivers, in a rectangular enclosure which features a proprietary ported technology for consistent performance regardless of space behind wall. They are optimized for wall mounting, rather than in-ceiling, and require a in-wall depth of 10.5 cm. Bose Flush Mount 191 Speakers Specifications 100W peak power handling 50W IEC continuous power handling 6 ohm rated impedance 88db sensitivity Required wall/ceiling surface area: Rectangular-faced speaker – 83 /4″W x 6″H (20.5 cm x 14 cm) Round-faced speaker – 111/4″ diameter (26 cm) Installation Guide Gallery