5-Pack High-Precision Transparent Crack Width Gauge, Scratch & Spot Measurement Tool for Precise Inspection of Surface Defects (Accuracy：0.01 mm)

Good product

works as advertised

These are not built well and for field crack gauge verification. Do not buy for construction. Cheap

A little too flexible but useable

A set of 5. I use these for registering scale on my macro photography. Very useful

First off, these little plastic gauges would be fantastic for measuring small cracks and holes with precision. And if I were using them for this purpose, that would be fantastic! But I'm not. Why did I get them? Because they're clear, flexible, and they have 80mm worth of metric measuring along the side! True, I can actually use the other gauges to measure line and hole thickness, to around 2mm or so, and I've used it for that purpose once or twice, but to have the high-precision (0.5mm!) 80mm ruler on the side is huge. I keep these on my workbench, and when I need to measure something less than 8cm, to within a 0.5mm accuracy, this is my go-to ruler. The fact that it's clear and flexible means that I can curve/bend it around items a little, which helps a lot. Not only do these have all these features, but you get a five pack of them as well, so you can have them on different areas of your workbench, or even have one on a desk or two, as well. It's very nice to have backups. I misplace rulers all the time, to having a few around is very helpful. In the end, if you're looking to measure cracks and holes at or below 2mm, or if you need to measure things with high precision, in metric, up to 80mm (at a precision of 0.5mm), these are essential. Solid build, flexible with a thoughtful design. These are an important part of my toolkit.

I got this Devonian ruler to use with my digital microscope. When inspecting/photographing objects at high magnification, I need an accurate size reference to appear within the field of view. A small transparent sheet like this, with well-defined lines and circular dots, is perfect. While fine print can be challenging for my old eyes, it turns out to be a great benefit in this situation, as it makes the measurement values readable under magnification. I snapped two digital photos (different magnification) of the ruler on the microscope stage to show how crisp and well-defined the printing is: the Lines are 0.5mm – 0.65mm wide and the Circles are 1.0 – 1.3mm in diameter. One ruler obviously does the job, but having five means I’ve got some backups, and even some spares to loan to my colleagues.

The idea is excellent: easy-to-carry handheld QC tool for checking the size of blemishes, pitting, holes, cracks, etc. It's exactly the kind of thing I've used before on projects involving bottling and packaging. Problem is... it's also the kind of thing I've designed and made before. It's just a piece of laser-printable transparency with a set of markings printed on it. And that's fine- it doesn't need to be anything more than that, but it would be greatly improved if the printing were not on the side that's in contact with the product being inspected. If you look at the picture, you'll notice that it's not difficult to scrape off the printing, and since the printing is in contact with what you're inspecting, you're going to wear it off all too quickly. If you're inspecting food, you run the risk of getting the printed material in or on the product being inspected, and that's not great. All in all, this is a good idea and it's usable the way that it is, but it's not worth the cost. The markings do appear to be accurate, though: it is a useful tool, just with some drawbacks.

Worst product. Worth only 100 rupees maximum. Plastic sheet with readings. Don’t buy