The watch, which remains unnamed but which company followers have dubbed the iWatch, will be Apple's first foray into a niche product category that many remain skeptical about, especially as to whether it can drive profits amid cooling growth in tech gadgets.

Apple will introduce a smartwatch with a display that likely measures 2.5 inches diagonally and is slightly rectangular, one of the sources said. The source added that the watch face will protrude slightly from the band, creating an arched shape, and will feature a touch interface and wireless charging capabilities.

The source said Apple expects to ship 50 million units within the first year of the product's release, although these types of initial estimates can be subject to change. The watch is currently in trial production at Quanta, which will be the main manufacturer, accounting for at least 70 percent of final assembly, the source said.