These double-action truss rods are strong, reliable and easy to install. The low-profile design requires a smaller slot in the neck than most other truss rods. They consist of two steel rods joined at the ends. When the nut is adjusted one rod becomes a different length to the other rod, causing the truss rod to bend. 2-way (Double Action) truss rods have the advantage of being able to bend in both directions. This occasionally becomes very useful, especially when very light gauge strings are used, or if the neck warps. Welded 2-Way Truss Rods are easy to install, requiring a straight slot.