KEF CI4100QL THX Rectangle In Wall Speaker - EachFeatures KEFs patented Uni Q driver array Ci4100QL THX is a THX Certified Select in wall speaker. A deep understanding of the filmmaking process and surround sound is at the very heart of every THX certified 2. 1, 5. 1 and 7. 1 speaker system. Ci4100QL THX Featuring KEFs sophisticated sit anywhere Uni Q driver array, which places the tweeter in the acoustic centre of the bass midrange cone, this allows both the tweeter and woofer to act as a single