Will fit the following shocks:
Our USA-made, custom-built M10 shoulder nuts are used in our Mazda Miata Shock Mount Systems and are designed to thread onto the above-listed shocks which have an M10 threaded shaft end.
These shoulder nuts allow you to use 1990-1997 NA Mazda Miata shocks with 1999-2005 NB Mazda Miata shock hats.
NA Miata shocks have a shorter shock body and less length on the threaded portion, which makes installing the NB shock mounts difficult as the bump stop doesn't allow the threaded portion of the shaft to protrude the shock hat like the NB shocks would. These shoulder nuts will plunge into the shock hat and allow you to connect with the NA shock shaft.