Denis Wick #5526 Practice Mute Trumpet/Cornet, Recommended
Most important feature is a lack of back-pressure.
Unlike other "practice" mutes tried, which are really only suitable for hotel-room or back-stage warmup, at best, this Denis Wick item does not have a problem with excessive back-pressure, which can be a real handicap for the student player, impeding proper "feel" and embouchure development. Serious business! Also, at least one of "the competition" has quite a sharp, penetrating sound, which, even though much quieter than an unmated horn, still "cuts" quiet noticeably. This Denis Wick #5526 has a much softer and much more musical sound, which along with the excellent "feel", makes for much more enjoyable practice and warmup.
This item should be standard issue for all beginner trumpet/cornet players; there is no substitute for "practice hours", and this Denis Wick mute can and will make good practice much more bearable for other household members.
Not "cheap", it's a real quality item. Special mention for the high-quality, thick cork gasket. Super!