If you click on a part number then "Additional Info" it says Tyvek type 10G
According to http://apps.webcreate.com/ecom/catalog/product_specific.cfm?ClientID=15&ProductID=25809
"Grade 10G (Formerly known as Grade 1020) This smooth form is what most people recognize as Tyvek. It has a smooth, stiff non-directional paper-like substrate, and can be used for printing, painting, making envelopes, and many other uses.
Basis Weight 2.0-2.2 oz/yd2
Thickness 7.3-7.6 mils
+/-3 Sigma Range 4.2-10.8
Strip Tensile (MD) 37-44 lbs/in
Strip Tensile (CD) 41-49 lbs/in
Tear Elmendorf (MD) & (CD) 0.8-1.1 lbs"
If you look up Tyvek 1020 it looks like it's a burlier version of homewrap (hard-structure)