The Transfer Register Box (TRB) was designed exclusively for use with WhisperValue DC fan and fan/light combinations. It provides room-to-room air distribution with ductless heat pumps.  Wall mount application fits in a 2 x 4 stuf bay.  Powered by 60 CFM transfer at 0.4 sone (based on FV-05VS3 fan).  Works with standard size HVAC registers, specific for use with WhisperValue and WhisperValue Lite Fans.