The Carbon Fiber D-Tube Neck Beam has been specifically designed to stabilize instrument necks due to its unique D-Tube structure. The Carbon Fiber D-Tube Neck Beam significantly increases both bending and torsional stiffness and weighs less than the removed wood!The D-Tube Neck Beam is available in both straight and tapered versions to fit virtually all necks. The tapered version is designed to be used on thin necks.