dimmutal, grit refers to the roughness of the sanding stick or sandpaper. As for sanding sticks the grits are usually classified :coarse, medium, and fine. With sand paper the coarser the grit the lower the number; 50 grit sand paper is very coarse, 1200 grit sandpaper is very fine.
Aside from repairing the canopy, you may be able to order a new one from the manufacturer for very little cost.
Hope this helps.