The sharpening wheels on your edge pro compact electric knife sharpener are made from bonded synthetics. Our wheels are manufactured according to strict tolerances in order to ensure the same high quality on each and every wheel that we make. The crossed ceramic rods put the final finished edge on your blade. Crossed ceramic rods create a fixed sharpening angle that lightly hones both sides of your blade at the same time, thus putting a polished razor-sharp cutting edge on your knife. Also, the crossed ceramic rods are excellent for giving already sharp knives a quick touch-up before use. Just a few, quick pulls through the sharpening slot is all it takes. Smith's recommends always using the ceramic rods for final edge honing after you sharpen using the synthetic wheels. Again, just a few pulls through the sharpening slot is all it takes.