#6 x 1 ½” zinc type AB. Type AB screws tap their own mating internal thread. They require a preformed hole for installation into metallic materials but necessary for wood or plastic materials. Combines locating point of Type A with thread size and pitch of Type B. Normal limitations of Type B apply. Has a general purpose bearing area and can be substituted in most applications for round, truss, or binding heads. Provides good control in driving and is the most recommended drive.