Machinist Square Precision Engineer Wide Seat Square 90 Right Angle Ground Hardened Steel Angle Ruler 4 x 2.5 Inch

Great on point . Had to make square stock for some high end stair threads and this tool showed exactly what I was teaching.

Excellent square for cheap. Checked for square using the parallel line test and they look perfect to me. Highly recommend.

EDIT - after my attempt to improve the accuracy of the square (described in my first review, below), it was still off just a hair - It's actually quite hard to hold the parts absolutely square while the epoxy sets up, so it wasn't a perfect fix. It was only off by about half a millimeter in 3 inches, but I decided to buy another and try for better precision. I gave this one to a friend to help him improve his edge-planing -- like me, he tends to lean to one side or the other, and having this little square is a great accessory to keep us planing at 90°. I bought another of these squares, hoping for better precision, and it WAS better...though still not perfect. However, the second one is so close to dead square that I can trust it to align the blades on my table and miter saws to zero, FAR more accurately than the indicators on the equipment. Like the first one, a few seconds sanding with fine emery paper softened the sharp edges and made it more comfortable to use. Based on the low price, and near-perfect precision, I raised my rating to 4 stars. ________________________________________________ I like the weight and feel of this little "square". But it wasn't really square - I did the line-flip-line test, and at the end of the 3-inch lines, they were off just shy of 1mm. That may not sound like a huge inaccuracy, but if you were to extend those lines out 12", the disparity would be about 3mm. Not acceptable. I gave it one light whack with a hammer, loosened the rivets just enough to get the two lines to coincide precisely. I'll drip epoxy into the joint, and clamp it at 90 degrees. I had two reasons to buy a small square: (1) I needed a tiny square to do frequent checks for 90 degrees when I'm planing a board's edge (I tend to lean to the right...sort of like my political views), and (2) to check blade setup on my table and miter saws. It was actually good enough as-is for checking board edges, but I want my saw blade setup to be spot on, so I really did need to adjust it to 90 degrees. One other minor issue, there were sharp edges all around, and a couple of small dings on one edge. It took me about 30 seconds with a scrap of used 220 grit sandpaper to soften all the edges. Hey, I read most of the reviews before I bought it, so I knew there was a chance it would be un-square. But at the price, and with a lot more 5-star reviews than 1-star reviews, I thought I'd take a chance on it, and I'm not too disappointed. With just a little work, it will serve my purposes well.

I use this little square for woodworking all the time. Absolutely all the time! You want to square up your table saw, you need this you're making a box you need to check the inside angles you need this. Very solid feel. I do recommend to apply some 3-in-1 oil as soon as you use it the first time to keep it from getting a little rust on it.

I use this to check all my other squares on. Dead on 90 degrees and a brilliant price.

The 4" x 2.5" one that I received was not square. I tested on a machined surface with different sides of two different 123 blocks. It was off by about 0.2mm at distance of 75mm. I could clearly see a gap with a light behind. Blue painters tape is so camera can focus. Sorry the pictures are a little grainy; It was hard to holding the camera still when so close.

Works well

Checked and it is 90 degree