A stock phone is not a refurbished phone, it is very different from a refurbished phone. A stock phone is an old or new model of cell phone that is not sold in the first place and then stored in a warehouse after it is released.
Most of the time, they are new phones, but because of the backlog of goods, they become stock phones. Refurbished phones, on the other hand, are those that have been disassembled from other cell phone parts and then left intact and reassembled back together.
Safety stock (or buffer stock) Because of the uncertainty of production demand, companies need to hold safety stock or buffer stock in addition to cycle stock. Those who hold this view generally believe that the average inventory level of a company should be equal to half of the order lot plus safety stock.
Expanded:
It is possible to have excess or insufficient inventory if you don't control it well. Insufficient inventory will miss deliveries, lose sales, upset customers, create productivity bottlenecks, etc., while excess inventory takes up too many resources.
These resources would be more productive if used elsewhere. Although excess inventory may seem to be the less harmful of the two maladies, if the excess inventory situation is more serious, the costs are staggering, and the situation is easy to control when inventory costs are high.
It is responsible for the overall management and control of equipment, including such management functions as calculating (inventory) requirements, initiating procurement or disposal activities, determining worldwide inventory data (quantities and monetary values), and deciding on the placement of equipment.
Baidu Encyclopedia - Inventory