couple rulers like the twister. Not sure i'll use it. I bought the rotary sharpener from a tv show and sent it back. Worthless. Had my copy of the receipt. Took 3-4 months before I got my refund. We argued about the time I had it in my possession. 1 week and dates of comparison were pointed out They said I didn't give it time. I tried it on 6 blades immediately and had DH try it. Won't do that again. If I can't just go to a store to get it, I don't need it that bad.