8658ENGAGE™ PV 8658 Polyolefin Elastomer? Ethylene-Octene Polyolefin Elastomer that offers excellent performance in electrical applications. Can be used as the base polymer inH8658 - תַּרְשִׁישׁ tarshîysh, tar-sheesh'; probably of foren derivation (compare ); a gem, perhaps the topaz:—beryl.