From google:

view. ** Accepted material thickness upto1/8"(125mil), easy handle any kinds of vinyl material, including sandblast rubbers (45mil in thickness)

So let's take this excerpt and examine it. If 1/8" = .125" and 1/8" vinyl is 125 mil, we can then conclude that 45 mil vinyl is .045" in thickness.

rant

Contrary to what they teach in school, the metric system is not easier to use. Granted, it runs on a base 10 calculation where the Imperial standard runs on a base 2 calculation. The Imperial Standard allows for more easily divisible segments in measurements. When is the last time that you heard someone ask for a 1.25cm wrench or a 6.4mm wrench that is 1/2" and 1/4" respectively. Either system has it's own advantages and disadvantages.

/rant

Whether the fatmat would be any better than dynamat I couldn't tell you. I haven't been in a vehicle that has ever had enough sound deadening material to make a difference in the quality of sound/ride.

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