I have the “Best Brass” mute. It fits way into the bell and kills Bout 90% of the sound. Intonation is okay but not perfect. I only use it when I need to practice when when someone is napping or in a hotel.
Here’s a discussion thread on a practice mute:
http://www.dwerden.com/forum/showthr...n#.W_QE2BpOmhA