This is my second one of these clips. I have tried several other brands and they simply do not perform as well. Yes, over time they might scratch your knife but you can avoid that by keeping it clean. My first clip only scratched when it was filled with slurry from the stones. I have used tape to protect my knives and this solved the problem but be warned on one of my knives the tape took off the black finish...that is a sign of the quality of the knife(not bought on this site). This is a good tool to get you use to the angle...over time I have used it less and less.