The present invention is a thumb rest that has a wedge body that attaches to a string instrument such as a bass or guitar. The wedge body has fastening holes, extruded ridges, contoured edges, and a string instrument facing side. This allows for a less permanent modification to the instrument. The fastening holes are circular holes that traverse into the wedge body. The extruded ridges are rectangular sections extending from the wedge body. The string instrument facing side is the flat side of the wedge body. The proposed implementation allows a user to remove and or move the thumb rest at any time.