The Fregat upper stage is a versatile and autonomous vehicle designed to inject large payloads into a range of orbits, including low, medium, and geosynchronous.

Fregat operates independently from the lower stages of its launch vehicle, with its own guidance, navigation, attitude control, tracking, and telemetry systems.

[6] Fregat uses storable, hypergolic propellants—unsymmetrical dimethylhydrazine (UDMH) as fuel and dinitrogen tetroxide (N2O4, also called NTO or amyl) as the oxidizer, which ignite spontaneously upon contact.

[7] The Arianespace-operated flight of a Fregat MT ended in failure on 22 August 2014 after the vehicle deposited two EU/ESA Galileo navigation satellites into the wrong orbit.

[8] The Independent Inquiry Board formed to analyze the causes of the "anomaly" announced its definitive conclusions on 7 October 2014 following a meeting at Arianespace headquarters in Évry, near Paris.

[15] The guidance computer on the Soyuz rocket's Fregat upper stage was mis-programmed, causing it to begin an unnecessary turn that left it in the wrong orientation for a critical engine burn required to enter orbit.

The Fregat-SB upper stage rocket used to launch the Russian Spektr-R satellite into orbit in 2011, broke into multiple pieces on May 8, 2020 creating even more debris than normal.

This version is a variation of Fregat-M with a block of drop-off tanks ("SBB" or Сбрасываемый Блок Баков in Russian) which makes increased payload capability possible.