A form of independent demand item management model in which a review of inventory on hand plus on order is made at fixed intervals. If the actual quantity is lower than some predetermined threshold, a reorder is placed for a quantity M x, where M is the maximum allowable inventory and x is the current inventory quantity. The reorder point, R, may be deterministic or stochastic, and in either instance is large enough to cover the maximum expected demand during the review interval plus the replenishment lead time. The optional replenishment model is sometimes called a hybrid system because it combines certain aspects of the fixed reorder cycle inventory model and the fixed reorder quantity inventory model. Also see: Fixed Reorder Cycle Inventory Model, Fixed Reorder Quantity Inventory Model, Hybrid Inventory System, Independent Demand Item Management Models