These have good low frequency specs., and the negation of having to have electricity or air, is a bonus in some applications. I still use air suspension for my low frequencies and then an interferometrically feedback controlled piston/servo/piezoelectric combo, for the higher frequencies. Finally then... I modelock my fringes, and use two photon injection to each cavity, through a distributed phase matcher. I guess my requirements are a little bit different than the norm?
