I have been using replacement blades for my 45mm rotary cutter for years, purchased from Harbor Freight. Once in a while I will receive a blade with a small spot that skips when cutting. Most of the time, all blades are very good and sharp and last a good long time. I order them in larger quantities, and have been very pleased with them. When I purchased the blades from other places, they were dull, and I was never happy with the products. There's no telling, wherever the blades are purchased, if one will have a dull spot - so for the price, can't beat these blades from Harbor Freight!