IN CEILING/IN WALL 4" 2-WAY PANCAKE POWERED BY SONIC VORTEXOur Sonic Vortex technology generates rich, deep bass and effortless clarity from what most people would call a 'back box', but is not. It is actually a compact, integrated tuned enclosure. This patented technology is a 'twist' on Ported Transmission Line design, that optimizes air movement to produce astonishing sound. The enclosure also keeps sound from bleeding to other rooms while adding 6 to 9dB boost in mid-lower bass.