![Image](https://massdrop-s3.imgix.net/product-images/MD-11674_20151015220132_355e81a817fc42de.jpg?auto=format&fit=crop&w=761&dpr=1)
Here is video with the sound difference:
https://vid.me/FZQ6
Edit: one more sound video:
GMK presentation video:
https://www.youtube.com/watch?v=W-hq_91BEX4
Edit2: These clips are not compatible with plate mounted switches.
After listening carefully to the videos, it seems that these things dampen mainly the sound of the keycaps hitting the switch case and not much of the return sound of the slider hitting the case on the inside.
I managed to do the same effect with some rubber foam sheets ant at a fraction of the cost: http://imgur.com/a/BmQ6b