Apple is unveiling a new version of its iMac desktop computer that's one-fifth the thickness of the old model around the edges.

At 5 millimeters around the edges, the new iMac is thinner than most stand-alone computer monitors. It bulges in the back, however. Apple marketing chief Phil Schiller did not say how much.

The new model achieves its severe thinness in part by eliminating the optical disc drive. Apple has been leaving those drives out of its most recent laptop models as well.

An iMac model with a 21.5-inch (54.6-centimeter) screen will start shipping in November for $1,299 and up, Schiller said. A 27-inch (68.5-centimeter) version will start at $1,799.