Originally Posted by gramalama9
The difference is in the hole in the blade....the notched holes will not fit Martelli cutters. The round holes will, as well as Fiskar's. HF has a round hole so if you are trying to use it in an Olfa cutter, it will not perform.
I have two 45mm Olfas and HF Blades is all I ever use. I did get a package once that left threads connected. 'when I took them out and examined them I found a tiny little nick caused by the knife I used to open the package with. I am more careful now when I open the pkgs and have never had any problems with the blades after that!