Astro Pneumatic 1/2” Drive Head In 3/8” Ratchet Body Nano Ratchet 91210 The Astro Pneumatic 1/2” Drive Head In 3/8” Ratchet Body Nano Ratchet 91210 is a 1/2” drive ratchet in a 3/8” ratchet size format. The Nano 1/2” head is 45% the size of the most popular 1/2” competition and the same size as 3/8” wrenches. 72 tooth, 10” long, quick-release socket retention, solid teardrop handle, full chrome polish finish. The Astro Pneumatic 1/2” Drive Head In 3/8” Ratchet Body Nano Ratchet 91210 exceeds ASME torque standards for 1/2” drive tools despite its miniature size.