This is a homemade trombone bell ring. Width: 10mm, Thickness: 1.5mm This is a great way to try out a bell cut or to see if a bell cut would suit your instrument. Furthermore, it was created with advice from professional trombone players in the Kansai region and a well-known repair shop. I made a large quantity for myself and am selling the extras, so why not take this opportunity to experience a simulated bell cut?