This is a three layer sound deadener by Asylum Audio. This product has three layers; Butyl, with a metal tin type layer, topped with a thick foam.

This product not only helps against excessive vibration due to the butyl layer, but it also helps to insulate the cab from heat and sound. 

This is my favorite sound deadener product on the market today.

This is one large sheet which is 10.7 sq ft (19.6"x78.7") of material. 
3mm Foam + 1.5mm Butyl Rubber, Foil .004"
It is rolled into the packaging instead of folded so that the foam does not become torn or creased.

Make sure you install this product onto a clean surface. It helps a lot to use a sound deadener roller as well to help the product adhere. Rollers are available and sold separately.