The aluminum composite tube around the threaded rod is intended to provide additional stiffness to the stinger. Often times these are shipped together and they are installed and used as is for modal testing. Many times the aluminum composite tube provides too much lateral stiffness and may cause distortion of the measurement system. One way to determine the effect is to test the structure with and without the aluminum composite tube and further compare these results with a longer stinger configuration. If there is no difference in any of the measured drive point frequency response functions then there is no concern. But if there are differences, then assessment of the measured functions and which stinger system is most appropriate for the modal test needs to be identified.