TMS Kobo Original Acoustic Improvement Goods Rotary Spacer-kun (Titanium) ver2 Limited production and workshop exclusive As a model change, the materials have been reviewed to enhance resonance. However, as there is a tendency for the sound to become slightly harder, heat treatment has been applied. This is an acoustic improvement device to be inserted between the rotary caps of a horn. It changes the ease of sound production and resonance. It can be used with Yamaha, Alexander, and Holton horns. It is also likely usable with tubas and trombones. Outer diameter: 21.5mm, Thickness: 1.5mm, Hole diameter: 10.5mm Made of titanium Due to the increased cost of materials, the regular price is now 3000 yen.