Robert Sorby 5/8" Tool Rest Adjustment Collar. The Tool Rest Adjustment Collar (TRAC) solves a common problem for every woodturner while turning. Frequently turners require a new tool rest height position, and when the locking handle is released, the tool rest drops, and the position is lost. The Sorby TRAC ensures the tool rest stays at the preferred set height, even when the tool rest locking handle is released, allowing the tool rest to be moved to a new position without the need to reset the height prior to locking into place. The TRAC allows the tool rest height to be easily adjusted up or down, by up to 1/2" (13mm), simply by turning the outer adjustment ring*. The Acetal seating disc allows the TRAC to operate smoothly and easily. *(TIP: Adjust the outer ring so around 1/4"(6mm) of the inner ring is protruding to allow for easy up and down adjustment.)