I had relatively high hopes when I saw the overwhelming number of positive reviews raving about this product; now I am beginning to question whether they are all stealth marketers!
I was well-aware that the whole theory about decoupling speakers from surfaces to prevent them from vibrating at certain frequencies and 'smearing' them (longer decay time), while reasonable at first glace, had negligible real-world meaning - google the keywords "ethan winer speaker isolation" for more discussion on the topic. My hope was to use the Iso-Pucks to simply stop the tactile vibrations (i.e. feeling the vibrations on my desk when I put my hand on it), I had no illusions of these making any audible (or even measurable) difference. Imagine my disappointment then when they failed to do even that!
My bookshelf studio monitors weigh in at 8kg with the heaviest corner just shy of 2.5kg, so still within spec. They currently sit on clear silicone bumpers, 7mm high and 14mm in diameter, one at each corner. I took them off one of my speakers and replaced them with the Iso-Pucks while leaving the other speaker as is; this way I could A/B test both solutions by sending the test signal to either the left or the right speaker only. I could not tell a difference between my €3 solution and these fancy over-engineered €85 pucks - in fact, if I squinted hard enough, I suspected that the Iso-Pucks were transferring more vibrations through than the bumpers!
My advice is: go to your local DIY store, get those rounded silicone bumpers before you spend your money. I got equivalent (if not better) results with those, you might too.