the sharpness of my scissors is never going to be tested long-term. I'm too clumsy. Inevitably, i drop the scissors or bump them off the desk and they always land on their tip. Happened again last week, and now i need to replace my Dr. Slick's Razor scissors. I liked the razors, but it did find the tensioning knob added a little bit of bulk to the pair and i never needed to adjust them. maybe others find it more useful over the long term, but i''ve never found the need to adjust the tension so i don't really see the benefit of it.