A retired millwright at a local particleboard factory (Panolam) told me that they ordered Zenith knives once.......only once. btw. Panolam does their knife grinding in house on some humongous, fantastically expensive automatic knife grinder that was made in Germany. I forget how many knives are in their chipper (or flaker, or whatever it is called), but it is a lot, and they don't get very many hours on them before re sharpening.