Craftsman digital level sensor?

Hello -
Friend of mine got one of those digital carpenter's levels made by Craftsman. It is very neat. Seems like the tilt sensor is inside a
metallic disk-shaped case, about one inch in diameter, maybe a quarter of an inch thick. Anyone have any idea what kind of sensor this is? How does it work, are they available for nerds? It has no numbers on it, and my friend doesn't have the manual for the level. And, he woun't let me take it completely part. Sheesh! Anyway, I was thinking the sensor may be good for robotic projects, and wanted to see if it is less temperature-sensitive (and cheaper) than Analog Devices or MEMSIC accelerometers, etc.
Thank for any information you might be able to provide.
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