I have used these ever since first reading about them on the board I think I had one that seemed to not last as long as the others, but at that price I can afford to replace them more often once in a while. A price of $4.99 might be for the package with the carpet cutter tool and extra blade. Those aren't the ones you want. Also, I have read where sometimes they stick together when you take them out of the package. If you put 2 of them in the rotary cutter, they won't work correctly.