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Nut & Bolt Thread Checker (Metric)

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$34.99

$ 17 .99 $17.99

In Stock

About this item

  • Each size has a nut and bolt checker on the same gauge. 21 of the most common metric sizes!
  • Thread sizes are permanently stamped (in white) onto each gauge.
  • Wire cable with loop for convenient hanging.
  • The individual gauges rotate freely on the wire cable for fast thread verification.
  • Gauges are a black oxide coated high grade steel.


Nut & Bolt Thread Checker: Metric The Metric Thread Checker is an accurate and easy-to-use thread identifier for both nuts and bolts. Each individual gauge features a male threaded stud on one end and a female threaded hole on the other. The Thread Checker is especially well suited for distinguishing between similar inch and metric threads. Conveniently assembled onto a wire loop, it's the perfect portable solution! Hang it on your shop wall or store it in your tool box for safe keeping. The Thread Checker, also known as a Thread Verifier, Thread Identifier, and Thread Check Tool is a great addition for any Home, Hobby, or Inventor's Work Shop, Auto, Motorcycle, Marine, ATV or RV Repair Shop, Heavy Equipment Repair Shop, Military Equipment Repair Station, Machine Shop, Fabricating Shop, Assembly Department, Production Department or Quality Inspection Station! SWTC-M21 Size Specifications: M3x0.5, M4x0.7, M5x0.8, M6x1.0, M7x1.0, M8x1.0, M8x1.25, M10x1.0, M10x1.25, M10x1.5, M12x1.25, M12x1.5, M12x1.75, M14x1.5, M14x2.0, M16x1.5, M16x2.0, M20x1.5, M20x2.5, M24x2.0, M24x3.0 Made in USA!


Dan S.
2025-09-03 16:08:10
Over the years I have collected a million different bolts, nuts, washers, and everything between. I also don't tend to organize them as much as I should, so I often will need another bolt of the same size/pitch and have to go between my drawer and the project I am working on guessing.This takes the guessing out of it! It allows me to quickly identify what the part is that I am looking for right where I store everything. Is it an essential tool to have in the shop? Nope. Is it something that I wish I knew about 5 years ago? Yep! It saves me a bunch of time and the quality on these are really good for the price.
Slim
2025-07-22 21:48:23
These are very simple - each unit has male threads machined on one end and matching female threads on the other, and they're all strung on a cable like beads on a necklace. It's a simple idea, but very nicely executed. All the threads are clean and accurate, they seem to be well hardened so the threads won't get messed up while testing different nuts and bolts, and each unit is clearly stamped with the size so it will never wear off. I purchased both the metric and SAE sets a couple of months ago, and they've already proven very handy to me. Using them is the quickest, easiest, and most reliable way I've found to identify "mystery" threads. These high quality tools are made in the USA.
Mike
2025-07-15 11:47:24
After reading many reviews and looking at several types of these I decided this was the one to get. I was right. Seen one review complaining about the cable making it hard to turn on a dirt bike stud but, I have used on my dirt bikes without any trouble at all. Maybe they lengthened the cable since his review. I was concerned the individual thread checkers had spacers but, they will slide as far as you want with plenty of length to get to any of them. They are precision made and very good quality of steel. The stamps are easy to read. I bought both metric and standard sets and VERY glad I didn't settle for the cheaper ones I seen. These will last forever. I have used them a lot and it's nice knowing the exact size and thread pitch on your nuts or bolts. Hey I'm organized.
PixellatedPolyGlot
2025-06-12 15:18:45
Tested the threads against some samples i've pulled off my metric motorcycle, everything seems good. For the price it's a reasonably good deal.2 minuses:1. One definite minus about these is that the markings are painted on, very poorly I might add. If they had been stamped or laser etched on I'd give it 5/5 stars for it's utility. The markings are almost illegible, they will most likely rub off over time through use and exposure to solvents.2. The durability of this item is dubious so treat it as it were made of glass. When in doubt buy a professional threading set from a machinist supply shop.
Scott
2025-03-21 11:32:52
We’ve all done it a hundred times….we shuffle down to the hardware store with a rusty, mysterious bolt/nut in our hand trying to find a replacement. You’ve already rummaged through coffee cans, mason jars, Big Gulp cups full of random screws, nuts, washers, broken pencils, and old Tic Tacs looking for one but you have every size except the one you need. Even if you did find one, you’d have no idea what size it is….coarse thread? Fine? Standard? Metric? It’s all a mystery. If only you had a Nut-and-Bolt Rosetta Stone to decipher it.Well, now you do, my friend. Just like the fancy unit the hardware store has to check thread sizes, you can check the sizes of your hodge-podge of hardware in the comfort of your own home. The individual checkers have a hole drilled through them and are attached to a steel cable (a long one by the way, almost three feet long). If the bolt or nut you’re checking isn’t attached to anything (ie, you’re holding it your hand), then the cable isn’t a problem, but if you’re trying to check something that is attached, you have to mess with spinning the entire contraption of cable and checkers. It hasn’t happened to me—and probably won’t, but I’m thinking of cutting the cable and making a holder for the tools. Maybe just a piece of wood with matching size holes bored into it so the pieces can set in there.The sizes are stamped (then inked) onto the sides, which is nice so you don’t have to worry about anything rubbing off. The stampings are clear and easily readable.There are other similar checkers on Amazon (similar to the ones in hardware stores mounted onto a nice piece of plastic), but I found that this one has a few more sizes than the others offer, plus I like the idea of being able to use each one individually (if the cable is cut). Trying to find the right size bolt to fit that threaded hole on your brake drum so you can use a bolt to press it off? Yeah, being able to use just a single one of these checkers would work perfect for that.I bought both the Standard and Metric sizes. The Metric ones have a black oxide coating on them and the Standard ones are zinc coated so it’s easy to tell which are which. All the machining is nice and clean with no visible burs or nicks.I know, I know. Having this still doesn’t mean you don’t need to go to the hardware store to buy the bolt/nut you need, but at least now instead of schlepping down to the hardware store to get your parts, you can order them online since you know exactly what size you need and maybe save yourself some money and time.Their website says it’s made in America. Amazon says USA is country of origin. There’s a plastic tag attached to one end of the cable that says “Thread Checker, United States” and then lists a patent #.You’ll love this. You should get it. You can thank me later.
BWR
2025-02-08 14:52:47
Love the idea but several of the little ceramic "spacers" between the thread checkers have shattered already. Not even sure they are needed to be honest but why the hell put something so obviously fragile in an item that's going to get banged around whenever it picked up?
JASON STULL
2024-12-31 18:45:34
This tool sounded wacky at first - numerous, small, threaded implements strung on a wire - but it works well. There are some other versions of this tool that have the sizes and pitches printed on the side of each thread checker, but these have them stamped and printed, making them seem more durable and less likely to get scratched off leaving no sizing information available.While I admit I was skeptical about the usefulness of having them strung on a wire - for instance when finding a thread size/pitch on the frame of a motorcycle - but so far there have not been any difficulties having them organized that way. Plus, none have been lost yet.For me, this tool's range of sizes is too broad. There are many more than I will ever need to use, and probably should have purchased the combination SAE/Metric one that this company makes, instead.That said, it's a quality tool, and I am happy with it. Recommended.
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