Karol:
The first time I used them I was disappointed, and then I realized that two had stuck together with the coat of oil that surrounds them. Once I put only one in, it worked great and this was an Olfa cutter, not that it matters. I tried to buy more on my last trip, but I guess the word is out in El Paso becasue the shelf was empty!
Sorry one of the tips disappointed you, but here is another. I will not be buying blades for a very long time because I purchased the blade sharpener wtih the grinding stones that sends the blade around as sharpens it. A blade can be sharpened on this over 100 times and it only takes 30 seconds. If it has a nick in it from running over a pin, it will not help much, but just for dull blades, it is the champion. I picked mine up, new, on Ebay for $50.00. It should pay for itself in about 6 months...but I am a longarm quilter and I quilt and cut something every day, so it may not pay for itself as quickly for others.