Faber-Castell is a professional Corporation. Faber-Castell USA is the only authorized distributor of Faber-Castell products in the United States. As such, any warranty / guarantee in the United States is honored only with valid proof of purchase from a verified Faber-Castell USA Retailer or Distributor. Currently, verified sellers of Faber-Castell products in the United States on Amazon.com are listed in the footer section of our website.