I use this warm up mute to practice in my apartment. It plays very well and it does not fall out of the bell of my horn. The sound is reduced enough so that my neighbours do not have to complain about the 'big sound' when I play without mute.
I also think it is useful that you can practice your intonation very well when playing with a practice mute, you are forced to listen more carefully to your sound.
The price and the quality are OK to me, I tested a few other warm up mutes and they were not as good as this one.