Good trumpet mute for indoor use?

I am looking to buy a trumpet mute for my friend who can only practice in her apartment. Any recommendations on what kind of mute would be good for indoor use, and possible brands too?

Good trumpet mute for indoor use?
Harmon mutes (think buzzing "Miles Davis" sound) are good because they mute the sound, but are used widely at gigs. I prefer, however, the Bubble Mute by JoRal. It sounds like a Harmon, but is easier to play and stays in tune better. Stone Lined also makes straight mutes, practice mutes and cup mutes. Yamaha has a "Silent Brass" system that is good for practicing, but I find it hard to practice with (you listen to the sound through headphones). Most music stores will have what you need, but for the long term investment, go with the Harmon/Bubble mute.