Bests & Worsts Reviews from Amazon

I was absolutely delighted to see this gauge at Amazon: exactly the design I was looking for (other gauges I have seen are clumsy to use). Sure enough, the construction and design are exceptional. In fact, this thread gauge is nearly perfect except for one fatal flaw: as reported elsewhere in the reviews, most of the threaded holes are incorrectly sized or the threading is defective. Here I think I can help the prospective customer by providing actual data. As it happens, I just got done sorting my machine screws/ bolts. The following list includes all of the sizes of known identity that I had readily at hand. I was able to verify my sample, because I have taps and dies for many of the sizes, and machine nuts of known size (to assure correct identity of the screws/ bolts I was testing). In the attached photo, the bolts/screws that fit are in their respective holes; those that did not are lying down in front of the gauge (where there are two vertically aligned holes, the screw closer to the gauge belongs to the top row). The metric tapped holes were more often correct: M4-0.7, M6-1.0, and M8-1.25 worked; M5-0.8 did not. Of this small sample, then, 75% of the metric holes were sized and tapped correctly. The results were much worse for the SAE threaded holes--that is to say, the ones more likely to be used by most US-based customers. Of the screws and bolts in my sample, 1/4-20 and 1/2-13 worked. Those that did not (listed in the order they are placed on the gauge) were the 8-32, 6-32, 10-24, 5/16-18, 3/8-24, 3/8-16, and 7/16-20. The defective tapping or sizing makes up 87.5% of the SAE bolts and screws in my sample! I hope the manufacturer reads this review and takes remedial action. In the meantime, I cannot recommend this product!