I was primarily concerned with the accuracy of squareness, so I compared it to my Starrett Combo Square, drawing lines with a 0.5mm pencil and both sides, right and left, checked. Dead. The same with 45s. The markings on the blade are also precise and easy to read. The blade snaps firmly into place, but when you slide the blade over your head there is a very slight roughness that I haven't investigated yet. That's why I've lowered the rating, but for the price it doesn't matter much and probably an easy fix. Therefore, this square is of great value.