Roth Sihon Viola Mute
The Roth Sihon Viola mute is a wire mute with rubber to dampen the strings
It stays on the instrument and slides up to the bridge when needed or down to the tailpiece when not required.
You fit it by squeezing together the middle strings and then push the mute down over them. The 2 strings when released will engage in the mute to secure it in place.