Insulation both temp and noise.
I removed mine from the 712 as it was in terrible shape.
It was fairly easy to remove using a Heat Gun, spatula, and some patience.
I ended up applying a Noise deadening material that you can roll on or brush
apply, takes several applications to get a 4mm to 5mm overall thickness. This
product has rust inhibitors, is high temp, and water proof. It's a Polymer base.
My wind tunnel ended up rust free.
Here's a link to the product I used as an FYI
https://www.secondskinaudio.com/sound-d ... rum-liquid