The most outstanding feature of the Best Brass Wah-Wah & Cool Jazz mute is its outstanding pitch. Generally, the Harmon style mutes tend to raise the pitch a bit, but not with Best Brass. Apart from its excellent intonation, it has a warm and engaging timbre, and of course comes with the wah-wah attachment, which is popular for an "old time" sound as well as for comical effects. Great sound, great intonation and reliable build quality are the hallmarks of Best Brass mutes. This one is for trombone. Aluminum construction.