For smaller pencil-style condensers of 3/4" / 19-20mm this works extremely well. I can hear an improvement in the sound using this, because it isolates the microphone from resonances or vibrations in the stand. I'm reducing one star because this type of mount does allow the mic to sag a little if mounted with one end further out than the other, so best to balance it in this mount. You can also use the mic lead to help hold its position.
Compared to rubber-band suspension mounts this is much more compact and easier to position, and more practical to mount two condensers on a stereo bar; for X-Y position this may be the only realistic way to get shock mounts on both mics.
These have been around for over 40 years and are well-proven. Mine have been working regularly for several years with no sign of deterioration. You may need to tighten the screw from the factory setting to make it stay in position, but that's all it needs. If mounting a mic onto drum or cymbal stands, this will improve the sound by reducing vibrations. It is one of those products I use more than I expected, and I keep buying more!