Proposes, where appropriate, replacement of previous prescriptive with performance requirements for six nominal elastomer hardnesses, for joint rings manufactured from natural rubber, synthetic rubber (polychloroprene) (CR), styrene-butadiene rubber (SBR), polyisoprene rubber (IR), ethylene -propylene terpolymers (EPDM) and nitrile-butadiene rubber (NBR)) and mixtures of synthetic and natural rubbers. The appendices cover purchasing guidelines, determination of ring hardness and compression stress relaxation, testing of joins in rings and photographs of typical examples of 9 of the 13 defined physical defects.