Bought the tonneau from GD. And because each car shell is made individually, and, as the builder drills and fits the front air vents and the fixings for the soft-top frame behind the roll-hoops, the Tenax fasteners do not come as an integral [fitted] part of the tonneau.  So, as this is one of those jobs you can't mess up, I had a proper car upholsterer fitter install the Tenax fasteners.