Panasonic FV-WC04VE1 Wall Cap for FV-04VE1 WhisperComfort ERV.  Unique design allows for single exterior penetration.  

• This unique wall cap allows both supply and exhaust air to pass through a single 5-1/2 inch exterior penetration
• The interior Y-adaptor connects to the 4 inch diameter supply and exhaust ducts and transitions to a single 5-1/2 inch diameter exterior wall cap.
• Both the interior Y-adaptor and external wall cap divides into dual chambers to separate supply and exhaust air flow
• The FV-WC04VE1 combines optimal function, minimum building penetration, and stylish design. (The FV-WC04VE1 wall cap is sold separately from the FV-04VE1)

Width: 11-1/4"
Height: 7"
Length: 32-1/4"
Cap is approximately 8-1/2" Square and 4-1/2" Deep