As a saw guide stair layout tool or rafter tool Johnson s 12 In. rafter square will help you get the job done accurately and easily. This square features Johnson s unique Structo-Cast molded frame that is both lightweight and durable as well as permanent molded graduations for making quick and easy measurements. This rafter square comes with handy markers that measure 2x4 board dimensions of 1-1/2 In. 3 In. and 3-1/2 In. you ll always find this square easily in your toolbox thanks to its fluorescent easy-to-see color.