Makes adjusting your truss rod a less painful and awkward experience.
Vintage-style truss rod nuts have very thin yet wide slots and are made of unhardened steel, so normal slotted screwdrivers will cause damage – as evidenced on many vintage guitars and basses. Proper adjustment involves removal of the neck for full nut access, and the Standard Driver provides firm contact over the entire slot width for damage-free adjustment. In order to have the best results, you should prepare your instrument and understand limitations of the tool.
A little background is in order. Early Fender guitars and basses use a "cross screw" nut for truss rod adjustment, which has two slots arranged in a crossing pattern. Cross screw fasteners achieved popularity during the early 20th century because a second slot was provided in case the first became damaged. Early Fender designers may have seen this as beneficial, especially since modern hex drive nuts weren't yet available. In addition to older instruments, many vintage reproduction guitars and basses make use of cross screw nuts.
Adjustment of cross screw nuts presents several problems. Nuts are made of unhardened steel which is soft and easily damaged. Slots tends to be very thin, yet the nut is approximately 3/8" (9mm) wide. As a result, standard slotted screwdrivers don't properly fit. Large slotted screwdrivers would be preferred due to greater width, but their tips are typically too thick to fit into the nut's slot. Smaller screwdrivers may provide a better fit but only contact a small portion of the slot with damage likely after several uses. For best-case adjustment of cross screw nuts, CruzTOOLS developed the GrooveTech Standard Truss Rod Driver, with a tip designed to firmly fit into the entire slot width. If you have a cross-screw equipped instruments, this should be in your tool box. It's oversized handle with extra-long shaft gives you a firm grip and allows for easy access.