S-2 graf unit

The S-2 graf unit is a type of warp engine used on Klingon starships in the 23rd century.

A rough equivalent of the warp drive used by Starfleet ships, the engine normally allowed a D7-class battle cruiser to catch up with a ship traveling at the speed of warp 9.

According to some intelligence accounts, other Klingon starships used different types of dilithium conversion graf units as warp nacelles.

Due to rough translations, it is possible that the word in Klingon actually translates more accurately to the English word "graft," as the Klingons are more historically known for grafting technology together.