1、EASY TO OPERATE: Adjustable limit block double pointer position, simple operating. Insert the steel needle with fixed value, and insert the steel needle against the straight edge of the limit valve block hole for quick position and easy marking 2、STABLE AND NON SLIP: Built in marking steel needle on the side of the ruler, safe storage. The adjustable limit module is firm and does not slide, and the position of the slide block is adjusted by rotating the nut, and the marking is more accurate 3、DOUBLE NEEDLE IN ONE: Knob type telescopic marking steel needle is integrated with the pointer, both convenient and safe closing, you can use with confidence 4、EASY TO MARK: Turn the needle CW to push the ruler body to mark. Select the required value, tighten along the pointer, the needle will stretch out one hand to grasp the ruler body, pinch the stop firmly with one hand, and push the ruler to mark 5、CLEAR SCALES: T square line drawing ruler come with clear and easy to read scale, very long lasting and wear resistant, to meet your using needs