Atrium8SDI has a unique, patented* single/dual input switch that combined with its ingenious dual tweeter array enables you to use the Atrium8SDI as either a single high performance stereo loudspeaker, or the left-or-right speaker in a high performance stereo pair. And you can use it practically anywhere, also has special military spec waterproofing features, including our patented water-resistant PowerPort® bass venting.