PSI3, magic calculator that determines your strategic maintenance parts inventory for your production lines. The answer to this difficult question: "How many parts do I have in Inventory for my Production Lines maintenance?" What is the best stock replacement? These stocks are usually determined on experience, and generally oversized compared to the risk incurs. Calculate the best number of parts needed and lower your stock maintenance in heavy proportions! A simple but very effective tool, guaranteed return, often at the first part!