Boy, Oh Boy! Towshend!

@rixthetrick yes exactly, filled with quartz sand.
@millercarbon thanks, will check them

As for Electrostatics not needing the benefits of Supension Isolation.
Within my local HiFI Group .
There was a investigation to try and find Isolation Footers that work offering a comaparable impression to my SolidTech 'Feet of Silence' and Audio Technica  'AT- 616'.

The lesser value choices were experiened up to IsoAcoustic Gaia Models.
The Gaia's got the vote for use under TT's and a set og Gaia's eventually ended up under a group members Quad 2912 Electrostatic Speakers.

I am due to listen to these speakers on the upcoming weekend, it will be my the first time in almost a year listening to this system. 
 

Speaker spikes are useless. Vibration is not limited by the small surface at the tip of the spike; it pass through regardless. And massive platforms don't help; low vibrations pass easily through all large surfaces. Concrete floors are not "vibration absorbers" and this is not like grounding a signal. The energy must be redirected through an effective isolator. 

The manufacturing industry has dealt with vibration for decades, using springs and ball bearings for vibration control of large machinery. While the scale is much smaller with audio equipment, the principles of physics apply equally. As a result, you see the most effective (and most expensive) premium isolation products apply either or both of these approaches.

I had a customer who made me some Harleyish floorboard inserts out of medium-hard rubber.  They work perfectly on my tile over concrete floor.  All equipment is next door in the ex-laundry room, with its two 110 volt 30 amp (10 gauge) outlets, converted from a 30 amp 220 volt dryer outlet.This solved several problems:  Plenty of reserve amperage from the two circuits, resonance to the electronics, clutter in the listening areas, and hiding and routing dozens of interconnects between the two preamps, three amps, three tuners, CD player, head amp, turntable, sub crossover,etc.  Cost: Under $100 for two outlets, 2 110v breakers, and two more outlet plates for the speaker wire holes on the wall.

I met Max Townshend at the Premium XFi show in Holland where he had a demo going on 2 pairs of identical speakers, one pair mounted on his platforms and the other pair on spikes adjusted to equal the heights, it was impressive. Basically he is isolating the speakers from mini seismic tremors (his explanation)

Equally as impressive was the demo of his super-tweeter. Adding the device improved more than just the very high frequencies. It was producing the upper harmonics of all instruments allowing them to sound more real.

A lot of you will be shouting ’but I can only hear up to 14Khz’. Well it doesn’t work that way. The harmonics contain much of the spatial information and provides clues to the performers relative position. If you hear an instrument that has had the harmonics removed you will be listening to a pure sine wave. Does not matter if it is a sax or guitar, if they are both playing middle C for example what you will get is a pure tone at about 262Hz. Now when the harmonics are present you are able to identify the instrument and it follows that the more faithfully and completely the harmonics are produced the more a piano will sound like a piano. It’s quite uncanny when heard.

Taking cognisance of the above it will be easier to understand why room treatment is so important. If all this info is left to bounce around the room unhindered the very fine detail (harmonics) is just a jumble, confusing the imaging and making it harder to identify vocals and instruments.

OP, I apologise for going off track but Townshend’s name triggered my memory.