The initials 'CT' stand for Compact Theater. Paradigm excels at producing giant sound in a compact format. The Millenia CT is a high-performance design inspired by the award-winning Paradigm Reference MilleniaOne speakers, winners of Sound+Vision magazine's "Product of the Year" award. It's a fully powered audio/multimedia system consisting of speakers and powered subwoofer. No receiver is required. Paradigm has made it super easy to start enjoying award-winning sound with the Millenia CT. Everything is included in one box: two premium satellite speakers with stands, a powerful ultra-slim subwoofer, all the cables needed for a simple hookup, and a control box that hooks directly to AppleTV, AirPort Express, or other streaming devices. The control box is perfectly sized to stack with AppleTV.