This document compares inventory control models in SAP and conventional methods. It discusses the reorder point (ROP) and economic order quantity (EOQ) models, as well as the minimum-maximum (Min-Max) model used in SAP. The document uses a case study of inventory for special grease to illustrate how the different models apply and compare total costs. It shows that the standard ROP model is not always appropriate when buying costs are low due to grouping multiple items in a single order. In these cases, SAP's Min-Max model provides a better solution and lower average stock levels. Rules of thumb for setting Min-Max levels are also discussed but shown to not consider all relevant costs and risks.