IsoBlock Silicone Isolation Feet (4-Pack) – Non-Adhesive Vibration Dampeners with Isolation Dots

They are fine. Not sure they will solve my subwoofer resonating in the bookshelf.

Using them to raise a turntable dustcover, so that cables can escape out the side. Coupled with some Velcro squares to hold 'em in place, works like a charm.

I expect them to have adhesive to stick to my speaker. They are doing there job.