A stitching awl is a simple tool with which holes can be punctured in a variety of materials, or existing holes can be enlarged. It is also used for sewing heavy materials, such as leather or canvas. It is a thin, tapered metal shaft, coming to a sharp point, either straight or slightly bent.These shafts are often in the form of interchangeable needles. They usually have an eye piercing in it at the pointed end (as opposed to normal sewing needles) to aid in drawing thread through holes for the purpose of manual lockstitch sewing, in which case it is also called a sewing awl. Stitching awls are frequently used by cobblers (shoemakers) and other leatherworkers. Sewing awls are useful for making lock stitches. The needle, with the thread in the eye is pushed through the material. The thread is then pulled through the eye to extend it. As the needle is pushed through the material, the extra thread from the first stitch is then threaded through the loops of successive stitches creating a lock stitch. The action is likened to that of a "miniature sewing machine". Styles may vary, as they are adapted to specific trades, such as making shoes or saddles. They are also used in the printing trades to aid in setting movable type and in bookbinding.