Drawing a long, straight line on a wall or other large flat surface can be difficult. You need a straight edge that may be many feet in length. Fortunately, you can use a chalk line to do the job easily. A chalk line, chalk reel, or chalk box is a metal or plastic case with powdered chalk and a string line inside. A hook ring is on the outside at the end of the string. A rewind crank is located on the side of the tool to wind the line into the case when the job is done.