The iso-pad 5 are a very useful studio tool. I use mine with my krk rokit 5 monitors.
Because the pad comes with in 2 parts, it is easy create different angles for your speakers. Speakers can be angled flat, up a bit, up a bit more, down a bit and down a bit more. So if you have a problem with speakers pointing at your chest, they are great.
The isolation is not great with these pads, though they do make a small difference. With the pads, a little bit less bass travels through to the desktop, meaning that there is less bass smearing and mud. If you don't have any other pads, these provide a small improvement.
Although the isolation is not great with these pads, they solved a problem for me, so they are a useful budget purchase.