A cryogenic density combustion booster
The cryogenic density combustion booster is a component that was installed on Din Djarin's N-1 starfighter. It was utilized by Han Solo at one point to support himself against the walls of the garbage masher 3263827 found on the first Death Star.
Around 9 ABY, Din Djarin received a combustion booster that Jawas had pilfered from beneath a Pyke repulsortrain.
Even though the cryogenic density combustion booster made its initial appearance in Star Wars: Episode IV A New Hope back in 1977, it wasn't formally identified by that name until Chapter 5 of The Book of Boba Fett, approximately 45 years later.