Screwdriver" is also known as "screwdriver", due to a wide range of uses, the shape of the makeup of different, say the most commonly used cross or word screwdriver it, the general first mark the outer diameter of the rod and then mark the length of the rod (the unit are millimeters), such as: 6 * 100 is the outer diameter of the rod is 6 millimeters, the length of 100 millimeters.