This is a BigBuzz American shank for horn. I purchased it from DAC and used it a few times, but I no longer need it, so I'm selling it. There is some surface dirt and minor scratches, but the shank, receiver, and screw-adjustable parts function well. A leather case is included. --------------- Innovative training tool 【Horn BigBuzz】 developed by Mr. Will Sanders (Professor at the Karlsruhe University of Music). Big Buzz allows you to adjust the size of the hole to your liking. The larger the hole, the more air leaks, making it difficult to play the instrument, allowing you to practice blowing more air into the instrument. After practicing with the hole open, When you remove the Big Buzz and play the horn as usual... ! The resonance increases remarkably, and you can play naturally.