In the top compartiments also bitumen and on the backside.
https://www.buildandlisten.com/loudspeakers/cno-grand/buildprocess/7984c06e-73f1-474d-9848-9a164168538c.jpeg/view
https://www.buildandlisten.com/loudspeakers/cno-grand/buildprocess/7984c06e-73f1-474d-9848-9a164168538c.jpeg/@@download/image/7984C06E-73F1-474D-9848-9A164168538C.jpeg
In the top compartiments also bitumen and on the backside.
