I bought this mainly to check the cabin altitude on my annual vacation flight. Exactly 8,000 feet. That is just what I expected.Appears to be well made and, based on just one flight, quite accurate.

This is a very good product, and could be either a primary measurement device or secondary, back-up weather and altitude back-up device. Was used to calibrate a Kestrel digital wind gauge, altitude and barometric pressure device - which is available at Amazon.com as well. (Could also work other way around Kestrel or like digital device utilized fine tune/calibrate this device?)Only gave 4- Stars, as dial is in fact somewhat hard to read in good light, especially those wear prescription glasses, dial does not glow in the dark, and even though in anti-ballistic case, should also be "rubberized" to absorb shock if dropped or compressed say in a rucksack, survey bag, or jacket-cargo pants pocket. Furthermore, dial little hard to manipulate as have squeeze fingers into anti-ballistic case- better design would have bee either dial extends through ballistic casing or some sort of small toggle.Despite the above, as far as one can tell highly accurate, and serious users such as US Military, back-packer's, mountain climbers-trekkers, hunters... and those into Van Life-RV lifestyle should really consider, as a "survival" tool in case lose all communications, get lost, etc.....! Or for those conducting activities in region's of world weather can change rapidly and drastically. Good thing about many Analog/purely Mechanical devices, is require no-or few specialized batteries, potentially high maintenance, and very difficult to "hack" possibly giving one's location and other pertinent information away, if this not expressly desired! Also they are very difficult to remotely tamper with in general, as well!

Perfect, no batteries, will work for a long time. Still works 2 yr later

works greatnice product

Back in March I attempted a hike from Mt Piños to Grouse Mountain in the San Emigdio Mountains in Southern California. I encountered a lot more snow than I had expected. The trail was 99% ice and snow and maybe 1% bare earth. With MicroSpikes the footing was no problem, but, after I got past the footprints approaching Sawmill Mountain, I couldn't figure out where the trail was even though I had hiked it quite a few times before. I had a compass and topo map, I could see Mt. Piños clearly, but I could not find the trail. In a moment of imprudent overconfidence I took off over virgin snow along what really, really looked like it just had to be the continuation of the trail -- and wound up 15 minutes later in what I realized was the wrong part of the woods. I was solo at 8500' on a Tuesday morning on a snow-covered, wooded mountainside way off the beaten track. Feeling like a total moron, I deployed the remaining morsels of my 2-digit IQ, turned around, and went back the way I had come.Post mortem analysis made it clear that I had made the swing to the west at least 150' too low. This got me to thinking that knowing how high I was might have kept me better oriented. I researched the use of altimeters in hiking and discovered that others held similar beliefs.I looked at altimeter watches first, but they seemed ridiculously pricey and did all kinds of extra foo-foo stuff that was of no interest to me. Plus a lot of people seemed to have trouble getting reliable readings from any that had a sticker price under $300 -- and from some that cost considerably more. Plus, the watches all had to have a battery to power the display. In some models the batteries weren't even changeable by the owner. At one site a purchaser titled his product review, "Great for picking up chicks."I decided I needed something more fundamental, and a modest amount of research turned up the Sun Altimeter 203. I decided to give it a try. It has turned out to be just what I needed.The Sun 203 is a simple pressure altimeter with an analog dial calibrated in 100' increments from 0 to 15,000'. I feel like I can interpolate the pointer position and get a value within plus or minus 10' or so -- plenty good enough for orienteering purposes during mountain hikes. The instrument is robustly constructed from a molded polymer that looks like ABS, and it is not petite: It is 2 5/8" wide by 3 1/4" tall by 1" thick. It comes with an attached lanyard that I wear around my neck. The dial is large enough for me to read while wearing my distant vision glasses, and as I become more familiar with the instrument, it gets easier to read accurately with a quick glance while in full stride. Since I'm doing hikes with 3000' or more of elevation gain, I find it, if not helpful, at least comforting to know exactly how I am doing with the vert without stopping to look at the topo map.A pressure altimeter is basically a barometer with delusions of grandeur. It is really good at accurately sensing changes in atmospheric pressure, but the conversion of these pressure changes into actual altitudes is subject to two principal kinds of errors. On type of error is caused by changes in atmospheric pressure due to weather systems. You can sit in your living room and watch your altimeter tell you you are going down while a high-pressure cold front passes through. The second type of error is caused by significant changes in temperature. You can sit on your camp stool and take an altimeter reading at sunrise when it is 30°F, while away the day at the same spot until it is 75° that afternoon at which time the altimeter will tell you that you have ascended maybe a hundred feet or more. What you do about this is learn to understand thoroughly how these phenomena operate and re-calibrate your altimeter during the day whenever you are at a physical location where the altitude is known. Google "The use of altimeters in height measurement" for an excellent article about the use of altimeters while hiking in Scotland where both temperature and pressure are subject to considerable change on any given day.I've been hiking in the mountains of Southern California where the macro air mass has been quite stable and temperature changes have been moderate, and the Sun 203 has seemed to be just about spot on at every point of known elevation. My environment has been much kinder to altimeter accuracy than Scotland. What needs to be understood in all this is that the altimeter is not like a digital watch or a calculator. To get accurate information from an altimeter under every circumstance you may encounter while hiking you have to know a few things and make a few adjustments when circumstances warrant.I'm finding that having an altimeter along while hiking adds to my enjoyment. Maybe someday it will help me solve a knotty navigation problem like the one I bonked in March.Three more things you ought to know. First, The Sun 203 costs one fifth as much as the cheapest altimeter watch worth considering. Second, you can't change the batteries in the Sun 203 because it doesn't have any. It is 100% powered by atmospheric pressure forever. Guaranteed. And, last but not least, if a Suunto altimeter watch helps you pick up chicks, you won't be able to handle all the action you will get with a Sun 203.