We bought these for a new employee in our sheet metal bending shop measuring shop. We don't usually have a problem with General brand protractors, but this time it's different. The angle marks on the right (0-90) were about 1/2 degree, while those on the left (91-180) were fine. It will probably be fine for carpentry or other crafts, but not for precision manufacturing. We ended up throwing them away as they were only $13 and not worth the hassle.