Unique single direction Fine adjustment at base. Holds 3/8" and dovetail. Noga unique central locking mechanism with spring loaded bearing. Powerful 70 lbs. on/off magnetic base with fine adjustment on the base. Bottom arm length: 2.20" Top arm length: 2.00 WARNING: This product can expose you to chemicals which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.