I ordered this item at the same time that I ordered a J.A. Henckels 8 Piece Stylus Block Set. When I first received this sharpener, It worked well at keeping the knives very sharp. After using it for around four months, honing the knife blades about once a month, I needed to open it up and reverse the carbide inserts because it had stopped sharpening the knives.Within another four months the sharpener was completely useless. It wouldn't work any longer. So the carbide inserts do need replacement after 30 to 40 times of use, and the carbide inserts that need be replaced are at a cost almost equal to what I had paid for the entire unit the year before.The "5 to 10 years of use between blade changes" on the product page is a complete exaggeration. I, just two weeks ago, paid over $7.00 to Amazon (best price on the web) for a new set of replaceable blades, after 8 months of light use.