Pretty accurate for $15! The metalwork is a little rough, but I expected that. One thing to watch out for is the auto-off feature and the on/off button don't actually turn it "off".

The display turns off, but there's still a charge going to the LCD which you can see in the silhouette of the number segments.

The battery on mine lasted for a little under a year, but I'd recommend removing the battery if you aren't using it for a while. I have a feeling the manufacturer knew about that when they put the little cut-outs for a couple LR44 cells in the provided case. ;)

For the money it's pretty good and repeatability was better than I expected. But that's about the only good thing I can say about them. The slide action is incredibly rough and makes a horrible grinding noise that makes you wish you feel like you're getting a root canal.

At first I thought maybe I was just unlucky but then I came across this: https://www.youtube.com/watch?v=WvszAb0Y0Ec

If you really need calipers, get these, they're more accurate than using a potato, but if you just want a pair, save up for a better set.

Out of the box, it didn't work. The reading was jumping all over the place, and eventually, I couldn't turn it off anymore (pressing the ON/OFF button didn't turn the calipers off).

But you can't really complain for $10. Sparkfun made it right though, so A+ to them.

These are not good, spend more.

I bought this a while back. From the very beginning, it was pretty much worthless. You zero it out, and then as soon as you move the sliding bar, the zero point begins to fluctuate wildly. I've never been able to get the same measurement twice for any target.

Had it put away in a cabinet; but, ever the optimist, I pulled it out again today and found that, yes, it's still all over the place.

I really don't think you should be selling this product at all. It's really a shoddy piece of engineering; not worthy of the SparkFun line of products. At this price, I suspect that most buyers, like myself, are inclined to write the purchase off rather than taking the time to request a refund or replacement.

Sorry that 1 star is the lowest rating I can give it.

Update:

After seeing the response to my post from SparkFun's Single T, I do regret that I did not take the time to pursue the matter through Customer Support. After several frustrating attempts to make the device work correctly, I, like many others, simply reasoned "what should one expect for 15 bucks?".

I will await reception of the replacement before making any further judgments on the usability of the device.

But I should not have forgotten that SparkFun is one of the most reliable and supportive sources of products, ideas, and support that I've ever experienced in years of building embedded devices. And your offer to supply a replacement, even long after my purchase, speaks volumes about the level of attention that SparkFun gives to its product line and its customers.

Thanks again to SparkFun for the critical support you've provided to my efforts.

It's a very good calliper, it seems robust and frendly. It would be better if the battery's cover comes with an screw or security system for prevent open battery's tape unintentionally , but it's a great Calliper, Really Really Great Calliper..

This set of calipers does indeed have some accuracy issues. Mind you, sometimes it works alright, but more times than you might expect the reading doesn't seem right and if you close them back to what should be zero you find that the reading is a bit off. These are alright though. As some others noted they're okay for the price and all in all I do find them useful.

Unfortunately this product does not work. You cannot turn it off, so the off/on button is basically useless! The measurements are not accurate and fluctuates wildly, even when not using and after zeroing it. To put it simply, this thing doesn't work.

I suppose there's lemons in any cheapish product, but the one I got has been working great for several years now. I think I've changed the batteries twice. I'm not a machinist (and don't need those kind of tolerances). This has been perfect for creating 3d models of parts and for the most part replaces the ruler on my desk : )

I got these a little over 2 years ago, and they recently stopped working, the reading will sometimes skip to a much larger value, or show exactly one-half the actual value (I suspect one or more of the greycode pickups are broken). Without any way to repair them I'll probably spend a bit more on a Neiko set

I've owned it for 5 years but I haven't used it a lot. When I need it it works very well and I've only had to change the battery once. The case is fairly sturdy which is nice for a delicate instrument and my not-so-delicate habits.

Having read a few of the negative comments, I would suggest that while they may simply have defective units, I don't experience mine fluctuating wildly. If I zero it pushing the button the way I would normally push the button, it does end up being off by 0.05mm, or 50 micrometers. If I touch the zero button very carefully and lightly, it zeros without this distortion. I presume this is simply due to the plastic material bending.

I should add that these types of calipers can never be perfectly accurate and I don't think we have any measuring devices in the world that are perfect, not even LIGO! They are accurate to within a certain precision and that appears to be around 0.01mm. The more you move it up and down the greater it should drift as (presumably) these use something like a laser mouse sensor, which I've worked with before.

Seams to be accurate and repeatable. But surface finish was awful. Had to take apart and take off the rough edges. A diamond knife sharpener seamed to be about the right grit. It now slides without it feeling "gritty". I like the plastic case. Still, for 1/10 of the price of a nice one, it will serve my purposes just fine.

So far, so good. I have checked it against known items and it appears to be accurate. I have used Mitutoyo calipers previously at work. For the price, these are good and better than the plastic one I had before.

I purchased this caliper in Feb (5 months ago) and the device is basically useless. Display is frequently and consistently off by 5mm as shown when I return to closed position. Display zeros fine, it acts like internal encoder is randomly dropping a turns count during a measurement. Some measurements are good, others are bad so I can't trust the caliper for any measurement. As a result I have scrapped a number of 3D prints because of display errors, wasting many hours in print time and expensive spool material. Resist the temptation and do not buy this caliper, in the end a simple steel ruler will be more reliable and accurate. Unfortunately I am outside my 30 day return window so SparkFun will not replace.

As soon as the Spark Fun package arrived, students were asking for one. These have proven to be a high demand item for the avionics and aircraft mechanic programs. Seems like I need to place an order about every other month. Good value!

As a little background I'm used to measuring things with Mitutoyo Calipers at work ($200+). The first thing I noticed is that this Calipers don't run as smoothly. I fixed that by adding some oil to the back rail and they still don't run as smooth but way better than before. Accuracy is pretty good, I actually expected less. The only defect I've found so far is that there is some kind of problem with the auto-shut down feature so I have already replaced the first battery with no more than 50 uses. I found a post somewhere on the web where they suggested to add an external switch, maybe I'll try it in the near future. Anyways, for the price this Calipers run they are a great deal if you are not looking for ±0.01mm accuracy or more!

Zeros and measures repeatably for my needs (mostly identifying part sizes). Rolling/sliding action is fine.

The hole-measurement prongs are too fat to easily measure 2mm holes.

I just got a 3d printer and got these to measure parts. They work as expected. No problems using them.