Depends on the length. Or at least it used to. At one time some of the lengths used in certain Norton drive kits were not available in the US. I used to have to buy them in 50 mm widths, which were available in the US, and skive them down to 40 mm width. I haven't checked lately, so they might now be available in the US in 40 mm widths. I've used lengths from 880 to 960, and I don't recall which was the difficult one to find.
Ken