I have had my first blade in for over six months,in which time I have made over ten quilts. It is still sharp and doesn't skip. Remember a tiny drop of oil on the plastic "bed" before you place the blade on will help. If the blade is dry, it will not handle properly. My husband did some research and all round blades are made by two companies and packaged for many different names. There are no special round blades for carpet and cotton.