Truss Rod Wrench for Nylon String and Big Baby Guitars with Truss Rod Adjustments Inside the Body. The Taylor truss rod wrench is a handy tool for making minor adjustments to relief in your the neck of your Taylor acoustic guitar. Use it to compensate for a change to heavier or lighter strings, or to dial in the right feel for your playing style. Features a nut driver on one end and a handy Phillips screwdriver on the other. • MFSKU 1317-11 • UPC 841060087200