Superior Material Adjustable multifunctional ruler is sturdy and durable. The ruler is made of high quality stainless steel and the angle bracket is made of zinc alloy, which ensures that it will not rust, deform or break easily High Precision Measuring range is 0-300mm, double sided ruler in metric and inch graduations for easy and accurate reading. At the same time, it combines a level bubble, accurately measure the balance to improve work efficiency Multi-functional measurement This ruler can measure a variety of data, such as right angle, l 45 angle, length, depth and width. Come with a built-in scriber that makes it easy to mark without a pen Adjustable Design The spring-loaded screw and efficient clamping system make it easy to remove and install the stainless steel ruler, and the smooth ruler makes it easier also sliding measurement Widely Used This ruler is suitable for measuring, marking, etc., to help you measure accurately. It is widely used in home, engineering measurement, housing construction and other places Note In order to get a more accurate right angle, the end of the steel ruler should not cannot be pressed against the rib (about 15mm) How to tell if it is a right angleStep 1: Draw a vertical line on a sheet of white paper (for example the handle to the right). 2nd step : Reverse the square and draw another vertical line on the first vertical line (so the handle to the left). Step 3: If the two vertical lines coincide perfectly, i.e. the angle of the square is a right angle