The English Starrett screw pitch gage can quickly determine the pitch of various threads. The gage consists of a substantial steel case with 51 folding leaves, each leaf having teeth corresponding to a definite pitch from 4 to 84 TPI (teeth per inch). Features a locking device at all ends of the case, so leaves can be securely locked in position for use. Leaves have a special narrow design, permitting checking internal threads in nuts, etc., as well as external threads.