Iran insists that it has developed its own clone (Bavar-373) of the Russian S-300 anti-aircraft missile system. Iran began work on the Bavar-373 began in 2010, after Russia refused to deliver S-300 systems Iran had ordered. International sanctions, plus pressure from the United States and Israel led Russia to cancel the Iranian order. Iran has issued progress reports ever since and Bavar-373 is supposed to be ready for final testing in 2016. The actual Iranian missile for the Bavar-273 is called the Sayyad 3 and it appears to be the same size and shape as the S-300 missile and carried in similar canisters. Iran insists that Bavar-373 is superior to the S-300. Now that Russia has agreed to deliver S-300s Iran will have to reveal if it believes its own propaganda about which system is superior.
The original S-300 was known to NATO, during the Cold War, as the SA-10 and it entered service in the late 1970s and was upgraded several times since then. One major upgrade came to be called the SA-12 and it entered service in the late 1980s. Finally, there was the SA-21, which was so different from the original S-300 that it was given a new name by the Russians: the S-400. These systems began entering service, slowly, in 2007.
Each S-300 battery consists of 4-8 launcher vehicles (each with two missiles, plus two reloads). There are also radar vehicles and a command vehicle. The S-300V/SA-12 missiles had a range of 75 kilometers and were considered somewhat similar to the American Patriot systems. Later models of the S-300V had some capability to shoot down short range ballistic missiles. The SA-10/12 launcher vehicle also contains a guidance radar. The most recent version of S-300 (S-400) is supposed to be (according to Russia) superior to the American Patriot. But while the Patriot has over two decades of combat experience the S-300 has none.
Meanwhile Bavar-373 is not the first anti-aircraft missile system Iran claims to have developed. In 2013 Iran announced it had built a factory to produce the Sayyad-2 anti-aircraft missile. This is an upgrade of the Sayyad-1, which was based on the old (1950s) Russian SA-2. Sayyad-1 entered service in 1999. Both Sayyad 1 and 2 copied much from the Chinese HQ-2, which is itself an upgrade of the Russian S-75/SA-2 system. Sayyad-2 appears to have incorporated technology from the American HAWK and Standard surface to air missiles.
Sayyad-2 is a two ton, two stage anti-aircraft missile with a maximum range of 80 kilometers and max altitude of 20,000 meters (65,000 feet). The Sayyad-2 has better electronic countermeasures than Sayyad-1 but it is still dependent on the ground radar for guidance to a target and is vulnerable to electronic interference. Sayyad-2 is believed to have a more effective warhead.
The Chinese HQ-2 has been in use since the late 1960s and has been upgraded several times with modern electronics, an improved warhead, better rocket motors, and more maneuverability and turned it into a much more effective HQ-2 early in the 21st century. Iran has been getting military technology from China for over two decades. This apparently included the tech for the solid fuel rocket motors used by the Sayyad-2 and possibly some of the electronics. If an attacker does not have good electronic countermeasures the Sayyad-2 could be quite effective. China also has lots of S-300 and may have sold or leaked technical data on that system to Iran.