This construction protractors consists of a protractor arm and square head protractor,the swing arm can be locked with the protractor head to use.They also can be separated to use. Angle Ruler:Our construction protractor tool has both length and angle measurement function,with adjustable thumb nut,after tightening the nut,you can easily measure 0-180 degrees and read the angle number,the angle ruler for wood is clear and accurate,it can measure the length (0-30 cm/0-12 inches),it's a perfect for fathers,men and women who are working in carpentry,construction and engineering. Adjustable Precipitatior Arm:The adjustable protractor angle finder features center positioning and scribing,and a nut that adjusts the protractor arm to quickly and accurately identify angles and draw straight lines by locking the knurled nut in the desired position,for setting bevels,drawing radial lines,measuring and marking angles. High Quality Protractor Ruler:The body of this adjustable woodworker's carpentry protractor is made of stainless steel with laser engraved measurements for clear readability and durability.With a thickness of 2 millimeters,the ruler is both lightweight and durable.If you're looking for a precise,sturdy angle measuring tool for your home,our woodworking protractor is just what you need. Multipurpose:Adjustable angle protractor is suitable for engineering,angle measurement,student drawing,architectural design,length measurement,a useful tool for craftsmen,designers,artists and engineers. Package Includes:1 pack of protractor angle finder.Ruler measuring length: 0-30 cm.Protractor measures degrees: 0-180 degrees.Size: 304 mm x 100 mm.