It's Haartz Sonnenland canvas, and like Fowvay mentioned.
I do personally recomment RaggTopp, I've used it on my NBC with very good results. However, if you use a very soft-bristle nylon brush on the roof when scrubbing, clean the brush first as to not get the little fibers everywhere.
It also helps to apply the sealer when it's warm (and preferrably in the sun). They say to wipe up any overspray, but, well, the overspray is pretty nasty. It'd be wise to wash the car first, and use quick detailer to clean the areas that get covered in sealant (which is almost everywhere). Or wet the body-only beforehand. Mine sat for a few days before I was able to clean it off. A pain, but it does eventually come off the paint.