This is a fiber straight mute for baritones and euphoniums made by Humes & Berg in East Chicago, Indiana.
This 162 mute is pre-owned but does not look to have been used at all. The paint has yellowed slightly from its original bright white and there are marks from handling. Otherwise it will do what you need to do just fine.
Shown fitted to a Yamaha 321 euphonium. Cork application is good, slightly cleaner than the current model of this mute.