A large electronics manufacturer is considering outsourcing the manufacturing of a diaphragm used in its large speaker. The company estimates that annual fixed costs of manufacturing the part in-house, which include equipment, maintenance, and management, amounts to $6.8 million. The variable costs of labor and material are $7.20 per unit. The company has an offer from a major subcontractor to produce the part for $12 per unit. However, the subcontractor wants the company to share in the costs of the equipment. The electronics company estimates that the total cost would be $2.8 million, which also includes management oversight for the new supply contact. The company must consume more than diaphragms to make the manufacturing the part in-house option least costly. (Enter your response rounded to the nearest whole number.)