In the end, they are right when they say you get what you pay for... how hard is it for a corner square to actually be square? Apparently, very hard! For a 100mm square that costs almost €9, it's unacceptable for it to lack perpendicularity and for the wide base to have a bend

Recently purchased for checking the perpendicularity of the saw blade to the base of the miter saw, as well as for checking the perpendicularity of small-sized frames and laminates.
The first disappointment came when I realized that the angle was damaged at one point, resulting in a small "tooth" protruding. It should be noted that it came to my hands through an online order, so it was impossible to check before purchase.
What I did not expect at all was the unjustifiable and uneven milling it has undergone in 3 points. This can be perceived in two ways. By touching it in these specific points, but also visually. In practice, if the outer side (of 10 cm) is placed on a flat surface, a gap is observed between the side of the angle and the surface. This results in the angle becoming useless, even to draw a straight line.
Deciding to return it as a defective product, and with a physical presence in the store where the purchase was made, I was surprised to find that the other angles (of 20 cm and 25 cm) of Luckhaus had the same problem. Some with less and some with more and more intense milling.
The same does not happen with the inner angle. This is why I rated it with two stars.
In conclusion, I am not at all satisfied with this particular product. I wish I could present what I mentioned above with images.