The Dial Set Level is an adjustable bubble protractor used with a number of popular Jackson Safety Curv-O-Mark tools, including #4, #6, #7, #8, #20, and #33. The protractor covers 180 degrees thru 2 90-degree quadrants. The bubble is cast in the aluminum dial for durability. Made of durable lightweight cast aluminum Reads in 2.5-degree increments Protractor covers 180-degrees thru two 90-degree quadrants