It is very difficult, particularly in the repair business, to have customers wait while critical parts are ordered. This leads to carrying items in stock. With so much at stake, inventory can easily grow out of control. Excess stocks may be carried simply to assure that no order is lost. This objective is contrary to keeping the inventory investment low, in the interest of saving money. Part of lean operations is reducing inventory and related expenses. The fist step is to understand the cause of the problem. Fundamentally, inventory exists because of difficulties in obtaining it. One aspect of this is order lead-time. Order quantity restrictions, or attractive quantity discounts, also contribute to higher inventory levels. Dealing with inventory issues may seem an overwhelming task. "ABC" analysis is an attempt to help managers establish priorities. "ABC" classification is an approach that divides inventory into meaningful categories to facilitate management and focus on the most significant ones.