I agree with the Yamaha Silent Brass recommendation completely. I've used many different practice mutes and the huge advantage of the Yamaha system is that you can hear yourself through headphones. This may seem like a gimmick to some, but you just can't hear your attacks with those other mutes. Sure, you can feel them, but the Silent Brass helps so much. Playing without a practice mute is, of course, the most ideal way, but if you have to use a practice mute use the one that lets you hear yourself! Plus, if you're in a hurry to get a session done and don't want to "hook yourself up" to the entire system, just use the mute. It still feels better, to me, that most of the others out there except for maybe the Denis Wick mute, and if I remember correctly the Yamaha mute does feel a little more free blowing than the Denis Wick mutes I've used before.