off-set spacer for truss rod repair, thick 5mm (. 200&;quot; x . 365&;quot;), set of 4 On Fender heel-adjust truss rods, the adjusting nut might have recessed over time below the end of the neck, because of wood compression or an earlier truss rod repair. These polished metal spacers fit around the truss rod in the channel. With three different thicknesses, they give you control of how deep the adjusting nut sits on the truss rod.