One of the architects that I do a lot of residential work for asked me to come to their office and examine a problem they've been having with some areas getting too much airflow. The ductwork is completely hidden, and the entire office space has plastered in grilles, so there is no way to install any sort of in-line damper. Previously, they had some grille-mounted diffusers (dampers) mounted over the grilles themselves. They've been happy with the results, and want to install them elsewhere within the office. I checked out the diffusers up close and found they were manufactured by "NuTone". I looked all over the internet and can't find any info on them what-so-ever. Anyone ever seen these before?