TubeNet

I have rebuilt my DW practise mute, so I can no longer test it in my various tubas. However that mute was specifically made for the wide belled Sovereign 981/982 Eb basses. These are a bit special by being fairly narrow down where the bottom of the stack meets the bottom bow. I think all of the 4 Besson variants 980/981/982/983 have the same bottom bow, so the DW mute would fit them. I would rather doubt that it would fit the Miraphone rotor tubas with their larger bottom bow and less wide, but longer, bells. It is more likely that it will fit the Yamaha 621 tuba series.

Klaus

Mine worked well on my 186. I currently use it with my Nirschl 4/4 and it fits just fine. The fit can be adjusted with a heavy duty foam tape (?--not sure what it is called) at the bottom and where it seals at the top. The tape was included when I bought the mute. Hope that helps.

My DW practice mute fits my Besson Sovereign 982 EEb perfectly, and I'm sure it would fit equally as well in the Yamaha 621. I say that because I also also use it in a Yamaha YEB 321. It's a tighter fit there, but still useable. As has previously been said, the mute comes with a kit of removeable tape that wraps around the opening , allowing adjustments to fit the horn for which it is intended.