This study investigates the dynamic behavior of an innovative mechanical device based on the inerter concept, which is typically employed in structural vibration control. An inerter is a device that produces a force proportional to the relative acceleration between two points and exploits rotational inertia, effectively increasing the apparent mass (inertance) of a system without adding significant physical weight [1]. This property makes it particularly attractive for dynamic applications. The focus of this work is on an enhanced version of the inerter, developed by integrating a conventional rack-and-pinion mechanism into a rhombic truss configuration [2-3]. This setup exploits a geometric amplification effect, determined by the diagonal ratio of the truss, to increase the overall inertance of the system. In this configuration, the inerter is connected along one diagonal, while the external excitation is applied along the opposite diagonal, allowing for amplified inertial responses. The research begins with the characterization of the conventional inerter to establish its baseline behavior. Subsequently, experimental tests are performed on the enhanced system under harmonic excitation, considering two configurations: a reference setup replicating the standard inerter, and an amplified configuration incorporating the truss. The study compares experimental results with theoretical predictions, aiming to assess the accuracy of classical inertance models across a range of excitation frequencies. Notably, for certain frequencies, the device's response deviates from classical inerter behavior, highlighting the need for the introduced refined theoretical formulations to more accurately capture its dynamic characteristics. Nevertheless, the results confirm that the proposed configuration effectively increases the apparent mass of the device, supporting its potential for future applications in structural vibration mitigation. REFERENCES [1] M.C. Smith, Synthesis of mechanical networks: the inerter. IEEE Trans Autom Control (2002) 47(10):1648–1662. [2] G. Alotta, G. Failla, Improved inerter-based vibration absorbers. Int J Mech Sci (2020) 192:106087. [3] A. Pirrotta, L.A. Di Nardo, C. Masnata, Theoretical and experimental investigation on an improved rack and pinion inerter. Nonlinear Dyn (2014).