Redmond, Wash. - Microsoft debuted what it's hailing as its thinnest keyboard to date.

The Bluetooth Mobile Keyboard 6000 ($89.95) comes with a stand-alone Bluetooth number pad, which will also be sold separately for $44.95.

The keyboard is said to measure just a few millimeters thicker than a AAA battery at the back. It's engineered to taper down toward the front for lighter weight and portability ease, and it comes with Microsoft's Comfort Curve design for an "ergonomic typing experience."

The Comfort Curve design "encourages natural wrist posture with a slight 6-degree curve that is easy to use with virtually no learning curve," said Microsoft in a statement.

The Bluetooth number pad comes with a carrying case. Both will be available in October and have a three-year limited hardware warranty.