The WALTx-2 is 
  a surface-mounted, weather-proof, speaker-level, UltraMatch™ volume control. 
  It connects between the speaker outputs of an amplifier or receiver and a pair 
  of speakers. The 1x setting allows the volume control to be used as a standard 
  non-impedance matching control. The 2x, 4x, and 8x settings allow it to be used 
  as an UltraMatch™ control. The UltraMatch™ volume control provides a method 
  of matching the minimum output impedance of an amplifier or receiver, in addition 
  to attenuating the volume. This eliminates the need for a speaker selector or 
  other impedance matching equipment. The volume is adjusted by adjusting the 
  amplifier signal output of the volume control to the speakers. All Russound 
  volume controls are manufactured using a high quality autoformer design which 
  provides long life, excellent frequency response, no heat build-up, and maximum 
  power transfer from the amplifier to the speakers.
The WALTx-2 is designed to provide volume control for outdoor or wet locations. It can be mounted on an exterior wall or hard, flat surface, as well as directly on a section on 3/4" PVC conduit. The WALTx-2 provides superior protection against moisture from rain, splash, or sauna.
All Russound volume controls conform to UL Standard 1492 First Addition, and for Canada, certified to CSA Standard 22.2 No. 1-M94. This certification assures that Russound volume controls are designed and tested for safety.
Features
Specifications