I'm doing some balancing in a new MRI suite and noticed that directly above the grilles are honeycomb looking contraptions installed in the duct. I was told by the mechanical contractor that these were supplied and required by GE for use in all rooms with their MRI machines in them. They are about 1 1/2" thick and in the same location on all supply, return, and exhaust grilles. Anybody seen these or have any information as to their purpose? Thanks!