The next modernisation, called the S-300PMU (Russian "С-300ПМУ", US DoD designation "SA-10f") was introduced in 1992 for the export market and featured the upgraded 5V55U missile which still utilised the intermediate SARH terminal guidance method and smaller warhead of the 5V55R but increased the engagement envelope to give this missile roughly the same range and altitude capabilities as the newer 48N6 missile (max. range 150 km/93 mi). The radars were also upgraded, with the surveillance radar for the S-300PMU being designated 64N6 (BIG BIRD) and the illumination and guidance radar being designated 30N6-1 in the GRAU index.