The ruler tool set includes the following features: - Ruler for measuring small items in centimeters or inches, you can measure in 2 dimensions or measure in width - Protractor to measure component detail angles, the largest measuring angle is 180 degrees - Bubble level to measure horizontal or vertical plane inclination, you can use table tilt alignment - The digital compass has the ability to measure the angle of rotation and is necessary for you to determine the direction - Flashlight illuminates when the power goes out or finds items in the dark, and built-in SOS signal - Night color warning light flashes when needed, you can change 4 colors