I"ve been using them for a while now, (HF Blades) and not had any trouble with them. I can't tell they have hurt my cutting mat any worse than the friskars blades. I may run into some in the future that don't "cut it" but so far have been very pleased with them. Bottom line, if they don't work for you, don't use them. For those of us that do like them, we will continue to save $$$. At least until I find that they are defective, then I'll take them back.