Sorry to agree with everyone. I have had them all...even the electric one...none work that well. I think the one you just run it through a few times, back and forth, helps the most, IF you do it after each project. The electric one made my blades worse. Now I have a friend who says they make hers sharp. I was so irritated by the way they ruined my blades that I threw it in the garbage. $60.00 down the tube...that REALLY irritated me. I buy on Ebay, make sure they are OLFA and change them often...like many more here.