For Model Rocket and Airplane Owners...

"AltimeterOne" is a rechargeable digital altimeter that reports the peak altitude of flight on an LCD display. Its tiny size and rugged construction have helped to propel its use beyond model rockets and planes to kites, balloons, falconry, and other sports and activities.

Specifications:

Size: 0.47" x 0.64" x1.93"
        (12mm x 16.3mm x 49mm)
Weight: .24 Oz (6.7 grams)
Useful Range: Up to 29,500 feet (9,000 meters)

 Click here for more info: http://www.jollylogic.com/products/altimeterone/