Negative-Stiffness-Mechanism (NSM) vibration isolation system offer a unique passive approach for achieving low vibration environments and isolation against sub-Hertz vibrations. 'Snap-through' or 'over-center' NSM devices are used to reduce the stiffness of elastic suspensions and create compact six-degree-of-freedom systems with low natural frequencies.
David L. Platus,
"Negative-stiffness-mechanism vibration isolation systems", Proc. SPIE 3786, Optomechanical Engineering and Vibration Control, (28 September 1999); doi: 10.1117/12.363841; https://doi.org/10.1117/12.363841