2 Here are the second layers of dampening products. On top is the Under Carpet Light (UCL) and on bottom is the standard Under Carpet (UC). The UCL looks very similar to carpet padding, but it’s an engineered product that has a lot of thought put into it, instead of just chipped up rags and lint squished together. UC is made up of a top layer of flexible, 1-pound-per-square-foot mass-loaded barrier material and a bottom layer of acoustical foam. We initially picked up the UCL to use on the roof panel, but because of how close the headliner is to the inner roof skin we decided not to put it up there until we have a headliner to check clearance.