I assume this is the first production chip from the Lockheed Martin X-33 Venture Star Advanced Technology Demonstrator test vehicles new “aerospike” rocket engine. The X-33 was to be an unpiloted vehicle, launched vertically like a rocket but landed horizontally like an airplane. It was expected to be capable of reaching an altitude of approximately 50 miles and speeds of more than Mach 11. This Lucite is in very good condition with very minor surface wear. It measures 3" in diameter.