PreSonus ISPD-4 Studio Monitor Isolation Pads

Standing a nearfield monitor straight on a desk or an unpadded stand couples the cabinet to the surface, and that coupling colours what you hear before the sound ever reaches you. The ISPD-4 pads decouple the speaker acoustically so you are judging the monitor rather than the desk.

They ship as a pair, and each pad splits into two halves. That gives you three ways to use them: a whole pad under a full-size monitor, half a pad under a small one, or both halves spread apart under a monitor lying on its side.