Kinex 4026-12-015 Solid Machinist Square 6 x 4 Inches (150 x 100 mm) DIN 875/1 (Square w/in 18 microns or 0.0007 Inches)

I bought the 4 and 6 inch versions. These Kinex squares are sturdy, well built tools. I checked the inside and outside edges against a couple of other accurate squares and found them to be dead-on. As a bonus, they don't come supplied with some junky plastic case that I would have to pay for and immediately toss in the recycle bin. For less than $20, these are a bargain for squares built to the manufacturer's stated tolerance.

Arrived in plastic with a good thick coat of grease and well protected in a box. I cleaned it off and checked it for square with another known precision machinists square that I also own.One verified the other to tolerances much finer than I could measure and plenty good for my cutting work - perfect! Exactly what I wanted.A light coat of CorrosionX or Eezox (prior to storage) keeps rust from developing on these types of tools before they go back into my toolbox. Never put them away with the sweat from your hands still on them.

I was a little skeptical of the quality for the price but I'm impressed. This is a great quality square and is well worth what I paid for it.

I've read the discussions about square/not square so you've got to test it for yourself. An old woodworkers trick, take a known straight edge, lay the square against it, scribe a line, flip the square 180 and scribe a second line. They should be parallel. The longer the scribed line the easier it is to check. I checked it with a micrometer, I got 0.0002. That's within spec.I'll never get that close with the wood I'm working with. This thing just feels solid. Heavy. Threw my old square in the trash.

Received the product quickly. Wiped off the protective grease and it looked good. Checked accuracy on a machined iron table saw top with a 123 block. Looked perfect on both inside and outside angles. Attachment of the upright to the base seemed rock solid. That's all I need.

This is a foundation tool. It is used to verify the angle of a blade or the resulting cut and all the things that happen after that are built on the accuracy of this tool - it is the foundation on which a project is built. It must be accurate.

Last night I spent hours in panic thanks to this little guy. I thought my miter saw had been totaled, because I had some nasty kickback, and when I checked it with this square, it said it was skew to the fence and the table. I spent hours trying to fix it, practically took the saw apart and put it back together. I was distraught, because nothing was working. Just when I had thought all hope was lost, it hit me, like a voice in my ear, to check the square itself. So, I checked the square with my l ruler and my speed square. Both said that this SQUARE WAS OUT OF SQUARE, not my saw. Overjoyed, I rushed to tell my wife the good news. With a smile she informed me that she had prayed not 30 seconds ago that God would reveal the problem to me, which was exactly when I had thought to check the square.TL:DR: God is good, this square is not.

Love these squares. Have had it checked at a machinist shop near me, and they told me that it is within tolerance. The quality is very good as well. Made out of steel, came in a nice little box with padding, and fully oiled to keep it from getting tore up. Have used it to square up my miter saw and table saw blades both, all of my cuts are now perfectly square. I own a couple of these in different sizes and plan to buy a few more. Company that sells these is pleasant to deal with. Sent me an email the day after it arrived to make sure I received it.