I was so excited to try those blades for my rotary cutter from Harbor Freight. My husband goes there all the time and really likes the store. So he bought me 4 packs of them. I finally put one in last nite. Oh my gosh! They were terrible. I thought maybe it was my cutter so I tried them in another cutter. And the same thing.......they skipped and just did not cut properly. My dull blade I was replacing worked better than the new one. So this morning I took them back to the store. They were so nice and did not hesitate at all about giving me a store credit as my husband did not save the receipt. I can't understand how some quilters said they worked so good. I tried mine in my Olfa cutters. Did they have different cutters???