I purchased 10 packs by mail from HF and so far have had no problems with them. But I recently purchased some 60mm replacement blades for my Olfa cutter from Joanns. It was a 5-pack with 50%off. Now I know why they were on sale. I have two 60mm cutters, replaced both blades from the same pack at the same time, one cuts beautifully, and the other has skippers in it, cutting in the same place on my NEW mat. So price doesn't always guarantee a quality product when it comes to rotary blades.