I am a conservatory student (classical violinist) from the Netherlands who lives with two other people in the center of a busy city.
This practice mute is great.
It's an absolute must-buy for both (professional) violinists and violists who practice late at night (with other people around) and for those who practice in hotels and such before concerts. It comes in a plastic case with a nice styrofoam cut-out. I haven't regretted this purchase to date.
Quick heads-up: The positioning of the mute on the bridge of your instrument may temporarily slightly affect the tuning of your instrument.
To fix this, carefully adjust where the mute rests upon the bridge, or just tune your instrument again with the mute on. Always re-tune your instrument after removing the mute.
Edit: After extended periods of use, the mute leaves dark marks on the instrument's bridge. I haven't noticed a decrease in quality of sound, but it's something worth keeping an eye on nonetheless.