Artino Practice Mute for Cello

Your bridge would have to be very thin for this mute to fit on it.
I bought this for a student to use at home to quiet their practice for irritable baby siblings. It wouldn't fit on their bridge and doesn't dampen the sound at all.
Expensive junk.

This a significant improvement over the heavy rubber practice mute. It gives a much higher degree of muting than the Ultra Rubber practice mute and the tone quality is much more pleasing. It still tends to have a rather thin nasal sound, but that likely can't be avoided with heavy mutes. The improvement comes mostly in the lack of strange low overtones that the rubber mute tends to have. The low frequencies are much better controlled with this mute! Perfect for midnight practice in a thin-walled apartment.
There seems to be alot of concern over the different metal mutes being too tight to fit on a standard bridge. This mute fits extremely tight, and I was a little worried the first time I attempted to put it on. But, with a little force, it was able to fit onto my bridge almost perfectly. It's sometimes a bit difficult to remove once its on, but after a little time of getting used to the feel, it has become easy to put on and remove. The metal has enough flex to it that I was able to feel it bend out a little bit the first few times I put it on. My bridge is a standard inexpensive Despau French bridge on an Eastman student-level cello. I expect this has a pretty standard bridge thickness, so I don't doubt that most people should be able to use this mute.
The rubber coating on the outside does a good job of protecting from scratches when you inevitably fumble it and it ricochets off the top of your instrument (I found this out the hard way, HA!). The pressure of it has left some very slight dents in the bridge at a couple points, but this hasn't affected the instrument's performance in the least, and it isn't cosmetically noticeable unless you're studying it very closely. My instructor was very impressed with the quality of the mute as well, and he said I made a very wise purchase.