Helix Swing Arm Protractor, 180 Degree, 6 Inch, Assorted Colors (60009)

I like everything about it. Makes reading angles easier.

This dude the trick. The adjustable arm is great for setting consistent angles.

Handy tool to keep in the office.

Good product as described makes measurements much more easy and good price

I sell my notes because I take thorough ones. And while a protractor isn't strictly necessary for diagrams in calculus, as someone who can't even draw a straight line or a circle that doesn't look like a deflated balloon, having a straight edge and circular edge makes my notes look more professional and attractive. You can also detach the angled arm when you need the inner semi-circle edge. The plastic is of high quality, doesn't shatter or scratch easily, and the best part? I take my notes on a digital notebook (ReMarkable II) and the pen and surface don't bug out when the protractor is used (though that might be more praise for the ReMarkable than the protractor - but the point is that the protractor is digital-surface friendly.) It's great. If you need a nice tight little trig/calculus protractor, this guy will deliver.