Panasonic Whisper Value DC Series
WhisperValue DC ENERGY STAR® rated performance-valued exhaust fans DC motors with SmartFlow CFM technology and Pick-A-Flow for speed selection to customize the air flow.
These low profile models have a 3 3/8" housing depth and it actually fits in a 2x4 stud bay. It also includes a unique L-shaped bracket allows the fan to be installed virtually anywhere in ceilings or walls.