Limited production and workshop-exclusive items. Copper-made "Aburi" series. Custom-made. Acoustic improvement goods to be inserted between the rotary valve caps of a horn. Changes the sound's resonance and how it hits. Usable for Alexander horns. I think it can also be used for tubas and trombones. Outer diameter 24mm, thickness 1.3mm, hole diameter 12.2mm. Made of copper.