We have had many discussions on the Harbor Freight carpet blades which seem to fit all the cutters (45 mm). If you use the search feature you can see about these and other brands. I am sticking with the Harbor Freight ones. I haven't yet had a bad one, although it won't surprise me, but they are cheap enough to offset that. I see that you are in Panama and probably don't have a Harbor Freight but they do have an online catalog.