This adaptor allows the larger monster truck wheels from J Concepts to be fitted to regular 12mm hex fittings that don't have the small raised boss section in the centre, such as Tamiya, etc. Its a direct replacement for the standard adaptor and the mounting screws can be reused.
The example picture uploaded shows the Tribute wheels with Firestorm tyres on a Blitzer Beetle chassis.
The author marked this model as their own original creation.