The S-300P (transliterated from Russian "С-300П", NATO reporting name "SA-10 Grumble") is the original version of the S-300 system which became operational in 1978. In 1987, over 80 of these sites were active, mainly in the area around Moscow. The "P" suffix stand for "PVO-Strany" (country air defence system). An S-300PT unit consists of a 36D6 (NATO reporting name "TIN SHIELD") surveillance radar, a 30N6 ("FLAP LID") fire control system and 5P85-1 launch vehicles. The 5P85-1 vehicle is a semi-trailer truck. Usually a 76N6 ("CLAM SHELL") low altitude detection radar is also a part of the unit.