I read a thread back a few months ago regarding the H.F. 45mm blades and thought I'd give them a try. The first one seamed to work fine (had to use the one between the first blade and cardboard because the plastic was stuck to the first blade). Well went to use the other blade and couldn't get it off the plastic. Opened up four more pkgs and the plastic was stuck to the top blade in all of them. Sprayed all of them with WD40 to remove the sticky plastic and thought I was in the clear. I tried three more blades before I found one that would cut. Also after using these blades my cutting mat is showing wear (mat is 4 months old). I know these blades are cheap but for me I can't justify the cost of my mat and sanity (OK I know that's already questionable).