Material Description. This specification covers the requirements of rubber compounds used for underhood fastener isolator grommets, classified to two (2) different temperature categories; Class A and Class B. Types are hardness ranges defined in Tables 2 and 4. Test requirements for approved compounds are intended to permit usage in the described temperature and engine fluid exposure environments

Class A: Silicone Rubber (>VMQ<); -40 °C to +175 °C continuous

Class B: Polyacrylate (>ACM<) or Ethylene Acrylate (>AEM<); -35 °C to +150 °C continuous

Applicability. Typical applications include cam, rocker, front and rear cover, M6 or M8 fastener grommets for vibration isolation