CatEye no Power Bicycle Computers
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."
Some cycling computers can display a power reading, usually in watts. They usually require a separate sensor - in some cases a special hub or crank arm. A few will estimate the value based on speed, cadence, rider weight or other data. "Optional" means it can read from a separate power meter or sensor. "Included" means it is calculated by the computer or includes the neccessary sensor.