The 5450 THOR is an outstanding all-round instrument with a lot of "hammer" sound. Developed in cooperation of Jens Bj rn-Larsen, formally of the Radio Symphony Orchestra Kopenhagen, the Thor features a 17.71" bell for great resonance plus 4 steel piston valves and thumb activated 5th rotary valve along with a .748" (.787" 4th valve and ....