Adjusting the suspension height will return the drive shaft angle to the appropriate value in response to changes in vehicle height, improving damage and lifespan. When the vehicle height of the S2000 is lowered, the bearing on the differential side of the drive shaft will no longer be in the correct position, and if excessive force is applied, it may be more likely to break. This drive shaft spacer serves to return the bearing position on the differential side to the appropriate value.
It is introduced on Ameblo's "M&M HONDA's Honda Honki."
https://ameblo.jp/mandm-honda/entry-12249305457.html?frm=theme