This Spindle Brake replaces the pin spanner wrench and makes tool changes fast, convenient, and safe. It enables one-handed loosening and tightening of tool-less chucks; simply slide the spindle brake disc down into place and the spindle is locked and power to the mill is cut. When the tool change is complete, just lift the Spindle Brake disc up over the top of the spindle and drawbar, and power is restored to the mill. Priest Tools has made this to exacting specifications in precision machining centers for our G0619 Mill; the disc is made of 303 Stainless Steel and the plate is made of 6061-T6511 Aluminum. The disc is symmetrical and operates the same whether mounted on its front or back. Made in the USA. Grizzly T30850 - Spindle Brake Flip for G0619