Storage of goods at sufficiently high levels in the value-adding process may allow the company to meet the customer tolerance time. But there are also disadvantages to stocking. Stock ties up capital and requires space. Due to limited shelf life (that is, the length of time an item may be held in inventory before it becomes unusable), goods may perish, become obsolete, damaged, or destroyed. Keeping an inventory only makes sense where stored goods will be turned over rapidly enough. Accurate demand forecasting, where possible, helps to achieve this.