Panasonic The ceiling-mounted models maintain their industry-leading performance and quiet operation at both 0.1” and 0.25” water gauge. The 50 – 110 CFM WhisperCeiling and WhisperLite models on display at IBS 2011 now come with a dual adaptor for 4” or 6” ducts, making the fan ideal for renovation projects. With a new central mounting system, contractors also now have more flexibility during an installation, since the fans are easier to position in challenging ceiling configurations.