The Ultra SS is incredibly popular and for good reason! They can genuinely transform the presentation of pretty much anything you put them under. The Ultra SS contains 4 technology pockets making it a lot more effective at transferring unwanted energy than the Ultra Mini. It does the same thing from a sonic point of view, it’s just what it does is more pronounced.
They work really well under most electronics and loudspeakers (unless they are exceptionally heavy which is where Ultra 5 & 6 become relevant), with the correct threaded adapters the Ultra SS fits where the spike would normally attach, the top hat can be loosened and adjusted for levelling purposes. There’s a knack for getting the decoupling just right and once correctly fitted and levelled the effect can be devastating!