Well maybe they improved it.i try a bunch of these years ago, and they were kind of bouncy. I tried them under my heavy Tannoy speakers, but they rocked too much. They worked great under my heavy Kenwood turntable however as good replacement for the feet.
SVS SoundPath Subwoofer Isolation Feet
I like to have these feet around to play with on various speakers/subs and I even put them under an AV cabinet. I just bought two new sets and noticed they’re SIGNIFICANTLY stiffer or "harder" than previous versions. Older ones are more "squishy". Has anyone else noticed this? It kinda shows me there was zero thought or engineering to them except to make something rubbery and bouncy and charge a bunch of $ for it.