What is the optional 3rd layer addition exactly?
The optional 3rd layer for the Pyrotect SFI-5 custom racing suit is constructed of Pyro X Inner Liner which adds an additional TPP of +7.5 to your suit's existing 21.6 TPP - 22.6 TPP rating. (TPP Rating: Divide this number by 2 to determine the number of seconds before a second degree burn occurs.)
It also adds additional weight. An additional 70 g/m2 to the weight of your suit. (g/m2 is: "Grams per square meter" which refers to the weight of the suit.) (70 grams equals approximately 2½ ounces)