Abstract: In a preferred embodiment an apex seal for a rotary combustion engine is disclosed having a hollow, thin wall, tubular, metal core member embedded in an extruded composite metal-carbon matrix. The seal is adapted to slidably engage the slot of the rotor in which it rides, and to sealingly engage the rotor housing against which it is spring and gas pressure biased. The incorporation of the hollow tubular core in the extruded seal permits a reduction in weight with no significant loss in flexural strength or wear resistance. It also provides gas pressure balance, end to end.