The book describes the K-Method which has been developed by the authors. The purpose of the K-Method is to negotiate and administrate a complex portfolio of customised materials, all belonging to the same purchasing group (e.g. labels). The underlying idea is to agree prices for specification features, instead of giving each material an individual price based on its unique specification. By doing so, a price formula will be agreed between the buyer and supplier which even defines prices of future materials with any kind of specification.