I love Olfa and have purchased them for years on Ebay and not had any trouble. Then early last year I purchased a pack of 10 on Amazon from a 3rd party seller. When I opened the blades in December, I could tell I had a pack of counterfeit blades. Every one of them was bad. I called Amazon knowing it was too late to get my money back, but I wanted to report the company selling them. Now I will purchase from a known seller and test right after I purchase.