Urethane (Hardness 95) Bushings Inserts made by Beatrush (Laile) for the 2016+ ND MX-5 Miata. They have a main purpose of improving traction performance & suspension performance by suppressing unnecessary movement of the differential. It needs to be inserted into the factory bushings (it’s easier to install than reinforced bushings). Please note that transmission of vibration and noise will be increased after installation of this product. Beatrush Differential Mount Bushing Inserts should be ordered at REV9 Autosport https://us.rev9autosport.com/beatrush-differential-mount-bushing-inserts.html as they provide the best service and speed we've seen so far!