Actual size. The Cyclometer 50 is not currently in production.

Altimeter Cyclometer 50 functions and specifications:

Altitude Functions:
CURRENT ALTITUDE: -990 ft to +19,990 ft in 10 ft increments, adjustable for barometric change
Trip Climb/Descent: To 19,990 ft in 10 ft increments (accumulated only while wheel is turning)
Total Climb/Descent: To 1,999,900 ft in 100 ft increments (accumulated only while wheel is turning)

Speed Functions:
CURRENT SPEED: To 128 MPH in .5 MPH increments
Average Speed: To 128 MPH in .1 MPH increments (calculated only while wheel is turning; averages up to 290 hrs without resetting)
Maximum Speed: To 128 MPH in .5 MPH increments
Cadence: 15 to 240 crank RPM (requires kit)

Distance Functions:
TRIP DISTANCE: To 1,999.9 mi in .1 mi increments
Total Distance: To 19,999 in 1 mi increments
Time Functions:
STOPWATCH: Elapsed time to 1:59:59
Clock: 12 hour

Details:
Dimensions: 21/8" X 21/4" X 3/8"
Weight: 11/4 oz
Display: Dual; UPPER NUMBERS 5/16" high, lower numbers 3/16" high
Operational Temperature Range: 0° F to 150°F
Wheel Sizes: Calibration for wheels from 9.6" diameter to 41.7" diameter in .04" increments

Data:
Altitude display updated every second when wheel is turning or when a button has been pressed within the last hour, every ten seconds otherwise
Speed display updated every second
Water Resistance: Waterproof

Batteries:
Two 1.5 v, 1.5–2 year life.
Use Avocet Altimeter 50 batteries or these equivalents– Ray-O-Vac RW44, Duracell D386, Panasonic SR43W, Eveready 386