I bought this mute for my Stomvi Elite piccolo trumpet as it claimed to fit a High Bb piccolo trumpet on Thomann's website. 
 
It did not. 
Wallace mute has different mutes for piccolo trumpets. 
This compact mute was too big for piccolo trumpet, at least for a long-model piccolo trumpet. 
 
I then tried to fit the mute on normal Bb trumpets, a Lawler C7 and a Burbank X5, the mute was hardly fit and it was nothing like the bestbrass practice mute which fits almost inside the bell. The TWC-M117 mute is mostly outside the bell. 
 
The mute did fit cornets (Yamaha and Besson) but I don't find it stable (sound, intonation, stability on the bell). 
 
Regarding the build quality, the stem within the mute was not centred. 
I own a Wallace TWC-M17 studio practice mute which is fantastic. Sadly the TWC-M17"C" (compact) is nothing close to the M17.