The following excerpt is from "Sport Rocketry". The intention is to allow guests to get a basic feeling about a kit. We strongly suggest that you get a copy of the referenced Sport Rocketry and read the entire article. Inside you will find many helpful hints in construction as well as other useful information. For more information, use the two links above.

"The Altimate I is billed as..."the world's smallest altimeter"."
"The Altimate uses a barometric sensor to detect launch and apogee, and then blinks out the peak altitude reading via LEDs."
"...the Altimate is approximately 1 by 1/2 inches in size. The 17mm-diameter Lithium battery solder to the bottom of the board, and the pressure sensor and other components sticking out, the altimeter is 1.15" long and fits inside an 18mm tube (Estes BT-20 size). The weight of the unit is 4.5 grams, including battery."
"The Altimate need to be placed in a payload section that is vented to the outside atmospheric pressure."
"For mounting in a much larger diameter tube, you'll want to rig some kind of carrier board..."
"The Altimate is turned on by a teeny slide switch on the end of the circuit board using a toothpick or bent paperclip."
"...the unit calibrates the ground level by measuring the air pressure....the unit continues to recalibrate the ground level reading while it sits waiting for lift-off."
"BonNova...now coating the Altimate I with an insulating acrylic conformal coating that seems to cure the "fingers on the circuitry" problem."
"The unit locks in...altitude and begins blinking the four LEDs in sequence to indicate the peak altitude with one-foot precision. The leftmost LED blinks out the number of thousands of feet; then the second LED blinks out the number of hundreds of feet; similarly, the third and fourth LEDs display the number of tens and ones. For altitudes over 10,000 feet, all four LEDs first blink simultaneously to indicate the number of ten thousands or feet."
"...flight tests of the Altimate showed that this system worked well."
"The minimum altitude the Altimate will report is 40 feet."
"The Altimate is powered by a 3-Volt Panasonic
-1632 Lithium batter, which should last for 30+ hours."

Overall, the article reviews the use of the Altimate and suggests it is a good altimeter for smaller and larger rockets. The article also reviews an alternate method to attach batteries and reducing its overall size to fit in a 13mm (Estes BT-5) tube.