Atrium Series Speakers exceed baseline industrial and military specifications for environmental endurance (ASTM D5894-UV Salt Fog, Mil Standard 810 Immersion, Mil-Std 883 Method 1009.8 for salt and corrosion.) Anodized Aluminum Tweeter Domes with Rubber Surrounds are absolutely immune to the elements, provide the smooth, broad high-end range you need for larger outdoor spaces Dual Input/Single Input Switch. Combined with its ingenious Dual Tweeter Array, this switch enables the Atrium 8 to be used either as a single high-performance stereo loudspeaker, or the left-or-right speaker in a high performance stereo pair