Smart Ruler Pro is the 1st set of Smart Tools collection. It integrated 6 simple and useful tools into this app. Here is the list. 1. Ruler - length. 2. ProtractorⅠ(Touch) - angle. 3. ProtractorⅡ(Plumb) - slope. 4. ProtractorⅢ(Camera) - goniometer, clinometer. 5. Surface level - sprit level. 6. Thread pitch - screw, bolt, nut. Pro version added features: No ads.