Fregat (Russian: Фрегат, frigate) is an upper stage developed by NPO Lavochkin in the 1990s, which is used in some Soyuz and Zenit launch vehicles, but is universal and can be used as a part of a medium and heavy class launch vehicles. Fregat became operational in February 2000. Its liquid propellant engine uses UDMH and N₂O₄. Fregat's success rate is 97.8% (with 2 failures in 93 launches), which makes it one of the most reliable upper stages in the world. Fregat has successfully delivered more than 300 payloads into different orbits. It remains the only upper stage in the world that can place its payload into 3 or more different orbits in a single launch.