The newest addition to the Best Brass line is a complete portable soundproof practice studio. Listen to your sound through earphones (included) so you won't over blow. Add resonance with a choice of 3 settings. A metronome is built in, and you can plug in a CD or Ipod for play-along practice. It's pricey, but not much heavier than the standard Best Brass Warm-up mute. This does protrude out of the bell a bit, so it won't store inside the bell in the case. This a well-made lightweight alternative to the Yamaha Silent Brass mute.