I am judging by other product reviews. I bought this protractor for minor and inaccurate but reproducible adjustments while aligning two separate pieces of hardware on my bike. The exact angles are not important; but there are repetitions. For $5 I figured I couldn't go wrong if the protractor was easy to use. This is exactly what I need and it works very well. I like that the device is small and light. This protractor is not intended for large construction projects and of course requires ease of use. The only downside I have is that it would be easier for me to use if it had a built in bubble level. I got over it and attached my own bubble level. Glad I found it on Revain and would buy more if needed.