Convertible models offer the advantage of two instruments in one.
Straight and F rotor sections can be interchanged by simply removing the tuning slide and loosening two adjusting screws. Open wrap models avoid sharp tubing bends for a more free blowing instrument. Bach Stradivarius 42 series trombones can now be purchased with Thayer TM Valve systems which eliminate sharp crook tube bends within the rotor itself, allowing for a free and umimpeded flow of the air column. Balanced Valve TM models eliminate the tight bends found in traditional rotors resulting in a less resistant F rotor section. The model 42KD offers an easily detachable bell for customizing.