"cycling-computers" CatEye Wireless Speed Altitude black
About CatEye - "CatEye is the leading manufacturer of cycle computers, lights and reflectors to cyclists in the world. Founded in 1954 in Osaka, Japan, CatEye has always been a leader in innovation and technology."
Wireless Speed allows a sensor to transmit the bicycles speed without a cable to the computer.
Some computers come with built-in altimeters, which will display the current altitude. GPS enabled computers can often do this more accurately.