Technical description: Silver-plated brass. Double principle, with alternative 1st and 2nd valve tuning-slides brought in use depending on whether the 3rd valve is operated or not. The windways through the valves are exactly the same as in Besson's "Enharmonic Patented" model (1904 patent) though the porting differs. Also with intonation slide (`trigger') on the 1st valve tuning-slide brought in use when the 3rd valve is operated for operation by L0. Valve type: Pe*-rinet-type valves.