Product Details:

• Breaks the Acoustical Barrier with Clear, Reliable, Hands-Free Two-Way Conversation
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  The Thru-Glass Two-Way Electronic Communicator is a self-contained, easily installed device that allows clear, intelligible two-way conversation in locations where security must be maintained. The unit is automatically activated when the clerk speaks for hands-free operation. Incorporating the finest electrical design, you can select either the 240V AC model, or the 12V DC battery powered model. Units are available in Standard or Deluxe Models with satin anodized finish.
  
  
  

• Diameter: 5 in (127 mm)
• Exterior Thickness: 1/2 in (12.7 mm)
• Interior Can Thickness: 3-1/2 in (88.9 mm)
• Color: Satin Anodized Aluminum