The Bach Stradivarius 42BOF Tenor Trombone w/ F-Attachment features a traditional Bach 42 bell, with the ultimate in tonal response and ability to change the color of sound, “Bell-free bracing” which allows the bell to vibrate freely, creating a quicker response with more clarity and projection, and a european designed “Open-Flow” valve, creating an ease of playability in the low register, while maintaining a great high range as well.