Dont usually keep past copies of the RPRA rules but I have looked back in the ones I have and cant find anything about not be able to use plastic rings, only thing I can find which might cover it is rule 97,"The council has the authority to designate the size,shape,Composition,type and quality of ring which shall be issued by the association," but this covers rings issued by the RPRA I would think, anyone know of another rule which might cover it.