Smart Protractor is in the 1st set of the Smart Tools collection (angle, slope).This app measures the angle and the slope of an object. This app includes two basic protractors.1. Touch Mode : for angle. after putting an object on the screen, touch the screen.2. Plumb Mode : for slope. this mode uses a weight and a vertical line.* Pro version added Features:- Ruler was integrated.- Protractor?, Surface level- Various Tilt units- No ads* Do you want more tools?Get [Smart Ruler Pro] and [Smart Tools] package.For more information, see the manual, Youtube video and the blog. Thank you.