Apple is expected to unveil the Apple Watch on March 9. Shipments will reach 4.8 million units in the first quarter and about nine million in the second, according to sources in the supply chain.

The sources also revealed that Quanta Computer is the sole manufacturer of the device and company vice chairman CC Leung has already gone out to plants in Changshu, China to monitor the process. Quanta declined to comment about its clients.