Xu Liping had a hand in building many of the rocket motors used in the military parade in September, the CCTV reported. The maximum error limit is 0.5 mm in powder precision for solid rocket motors. But for Xu Liping, it doesn't exceed 0.2 mm. "If you hit the metal shell and strike sparks, it will certainly cause an explosion - too fast for you to respond, no chance to run at all," Xu said.