In the interest of full disclosure, as a trusted and unbiased Amazon reviewer, I was able to request this product free of charge, except for having to pay tax on its fair market value.This set includes 4 micrometers in a well fitting storage case. The sizes vary from 1 to 4 inches. Being able to measure something up to 4 inches for this price point represents a good value. Also included are 3 calibration bars from 1 to 3 inches, although their usage is somewhat problematic.As far as I can tell the micrometers seem accurate, although I don't currently have anything that is calibrated with sufficient precision to test them. I will say that they hold their calibration well. I found it necessary to adjust the 0 point on each one. When I do this with the one inch one, open it to measure something and then close it to see if the 0 point has shifted, the variance appears to be no more than 1/10000. The micrometer has a vernier scale so it is easy to measure this from the scale. I haven't used micrometers very much, but I suspect for this price range, this is accurate.Adjusting the 0 point can be easily accomplished using the supplied wrench, but be advised you will need to use a bit of force to rotate the barrel. I suspect this is normal, you don't want the barrel to fall out of alignment once you adjust.The ratchets work will and that is what you want to use when you get close to clamping down on the part you are measuring. It is very difficult to measure the calibration bars and with the large ones if I try to use the bars, I get variances of about 1 to 2/1000 of an inch. There are a lot of variables here. To be precise you would need a holder for your micrometer as well as for the test bar. The precision of the bars is also unknown.Unfortunately, I don't have a precision block of material that I could use to check the accuracy of these micrometers. I have a small ruler with a painted (baked on) very smooth surface. If I measure with a vernier caliper I get .0505, .0505, and .0510. The vernier jaws are completely capturing across the width of the ruler which is about 0.7 inch. If I use the micrometer trying to measure in the same spot (which is capturing a much smaller area) I get 0.0520, 0.0520, 0.0524 - so a variance of about 4/10000. What does this prove - nothing. The ruler is not a finely dimensioned item; however, this does demonstrate consistency. Unfortunately, that is the best I can do. The vernier caliper is a digital one and a very inexpensive one. I don't think its repeatability really means anything. I use it as a ballpark tool and normally I don't work with something that requires such high precision.The fact that these micrometers maintain their 0 alignment and demonstrate consistency with measurements is a good indication to me. They rotate smoothly; there is no play, the locks work well and they are fairly easy to read - the numbering on the vernier scale could be a bit brighter, but that is not such a big fault.Again for this price point, I think these are good.

These micrometers seem to work correctly, and they feel solidly built, but I’m skeptical on their accuracy because they didn’t come calibrated from the factory. They do include “reference bars” to calibrate them to, but if they didn’t even start out calibrated, it makes me weary about the precision of those things as well. I don’t currently have a set of precision gauge blocks to independently calibrate them with, so I’m just hoping they are what they say they are.

This set of 4 micrometers allows me to measure anything up to 4" thick - the 4 sizes each handle a 1" range. So there's one for 0-1", 1"-2", 2"-3", and 3"-4" - plus a few replacement parts if you ever wear something out.One of the tough things for me with vernier caliper readings is always how tightly to squeeze while tightening the caliper on the thing I'm measuring. These micrometers take care of this - each one has a small knob at the tip that will release like a ratchet when it reaches the appropriate tension - meaning I can't over-tighten these when I use the ratcheting knob! Another cool thing I've never seen before is a little locking lever so you can lock a measurement in place on a caliper if you wish. Once you release the lock lever, you can spin the caliper again and adjust it as you wish.Included instructions are great for anyone unfamiliar with reading the last two digits of accuracy on this kind of caliper readout, though if they're not straightforward enough to understand, you can always seek instruction online - there are lots of folks out there who have made videos showing you how they work.The included carry case keeps everything organized. It's larger than I had expected, but it certainly gets the job done. The calipers rattle around in there the tiniest bit, but while it's audible it is of no danger to the tools themselves. If you want to keep it silent when you carry it, I would lay a little bit of foam or cloth on top of the calipers so they don't have space to rattle.

This set of micrometers is pretty well-built. They seem to measure accurately compared to what I have already. I know how to use these, but the instructions that came with mine were for the metric version, which doesn't help at all.

It never fails that whenever I need my digital mic the battery is dead. It does take a little more talent to use a manual tool like this, but you never have to worry about batteries! This can be accurate to .0001 as it says if you know how to use the vernier. The kit includes a spanner to adjust the mics if necessary, and I had to adjust them all just slightly. I don't like that the fine adjustment is made by "forcing" the barrel into position, but the course adjustment does require loosening the lock screw on the end. The 1" mic actually was able to read a very thin aluminum strip which my digital caliper could not read showing 0". The set also includes calibration rods for each tool, and everything comes in a nice plastic blow mold case. This is a great teaching tool that every shop should have - for demonstration and to use when the batteries die on the digital tools. The only thing I miss is the decimal to fraction conversion that is on the back of my other mic, but there are certainly enough ways to get that. I may past one inside the cover of this set (which I really think should be included along with a metric conversion chart.) If you have a need for a set like this I don't think you can go wrong with this one.