At its presentation here, Microsoft also added skateboard wheels to a Surface tablet, showing a photo of a Microsoft official standing on one.

The skateboard is not for sale, of course, but the demo indicated how Microsoft is hoping customers will see this resilience in its new 10.6-in. tablets running Windows RT as the devices go on sale Friday, starting at $499 for a 32 GB version. The WIndows 8 Pro version is due out in about three months, but no pricing was announced.

In previous demonstrations, including the in June, demonstrated the magnetically-attached Touch Cover and Type Cover for the Surface devices, and a metal rear kickstand that closes with a distinctive click. The click has inspired a catchy TV ad featuring dancers of all ages clicking the kickstands in rhythm. The covers are sold separately and start at $129.

Surface architect Panos Panay said the Surface was tested extensively for falls from 72 different positions. In his demonstration on stage, he dropped the tablet from about five feet onto a carpet and said it was fine.

There was little demonstration of the important touchscreen capability of Surface, but that's more an element of software and Panay and Steven Sinofsky, president of Microsoft's Windows and Windows Live division, focused more heavily on the tablet's hardware design. The Windows RT version will ship with Office Home and Student 2013, which includes OneNote, Word, Excel and PowerPoint. It won't support older Microsoft apps, however.