Angle Ruler:Our construction protractor 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 is clear and accurate,it can measure the length (0-30 cm/0-12 inches),it's a for fathers,men and women who are working in carpentry,construction and engineering. Adjustable Precipitatior Arm:The 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 exact lines,measuring and marking angles. High Quality Protractor:The body of this adjustable woodworker's ruler is made of Aluminum with laser engraved measurements for clear readability and durability.With a thickness of 2 millimeters,the ruler is both and solid.If you're looking for a exact,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. Ruler measuring length: 0-30 cm. Protractor measures degrees: 0-180 degrees Size: 304 mm x 100 mm Material: Aluminum alloy colour: Black + silver Package Contents: 1 x Protractors Angle Ruler Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.