The modal stingers are professionally made with the specific intent of being used for modal testing. They are intended to be used with modal shakers that are equipped with a through-hole armature design with a chuck and collet for clamping the stinger. The stinger can easily slide in the chucks collet until aligned and attached to the force transducer or impedance head, then tightened in place like a drill bit. The thin rod is very weak in the lateral direction, minimizing the transmission of transverse force inputs. The model 2150 series is just 1/16 diameter while the model 2155 series is 3/32 diameter, each with a 10-32 threaded stud brazed on the end to connect to the force transducer or impedance head attached on the test structure. An ordinary threaded rod with a conventional shaker (not specifically designed for modal testing) can be used, but set up and alignment are often difficult and cumbersome. Since these stinger designs are threaded throughout, attaching them to a tapped hole at both the test structure and the shaker armature, at the same time, is rather difficult. These are also typically much stiffer in the lateral direction, generating transverse force inputs, a significant source of measurement error.