Just clicked through to website and despite them saying they'd update it following my enquiry, clearly they haven't.Unfortunately the size of these and their inability to quote any weights they will support has always put me off. Foam compresses to the point of becoming useless and will disintegrate over time.
They answered by email to confirm max weight for these is 30kg. Compared to Auralex Gramma which will take 90kg.
Either which way, as mentioned above, for floorstanders imo just not suitable as seriously wobbly.