Z-Series 3/8″ Sq.Dr. Reversible Ratchet, L=280mm (72 Teeth). 3/8″ Square drive, Z-Series, Longer 280mm Length, Fixed Head, 72 Tooth Ratchet. The patented design of the 72T incorporates dual pawls. Ko-ken has ensured that their hallmark low backlash and small size are preserved.