Monroe Nivomat Self Leveling Dampner.
THIS IS NOT A SHOCK ABSORBER.
This is a self-contained and self energized unit, which automatically and silently optimizes front-to-rear suspension balance. It automatically keeps the suspension level.
Note: These can only be used as a direct replacement on vehicles that already have a Nivomat suspension from the factory. They are not for adapting to non-Nivomat factory suspensions.
The image used here is a general representation. Your specific unit may have different mountings on the ends, but except for that, it will work the same way and is the same kind of Nivomat unit.