KenS wrote:This sounds like the scientifically designed "Mahler Tape". This black tape when wrapped around the bottom bow gives your horn the perfect deep sound for playing Mahler.
Also made is a Tchaikovsky model. The "Tchaikovsky Tape", in red, when wrapped around the bottom bow, provides that extra brightness when playing Tchaikovsky.
Both have been scientifically proven to provide the timbre needed when playing either Mahler or Tchaikovsky.
I saw both of these demonstrated years ago by Keith Brown.