That is an absolutely beautiful helmet Mark! My very favorite. The silver trim is especially attractive. As far as I know, the 1906 regulations were only issued as a now extremely rare publication in which each uniform was printed on a separate card and preserved in a blue cardboard folder. Below appear all the uniforms to be worn with the pickelhaube. However, not all helmets are depicted as you can see from Henry's post of the three metal elite helmets. The use of feathers on helmets is not entirely documented as well. For example, the Puebla museum helmet appears to be the dress helmet of a President's aide that Henry posted, the one on the right of his three. However it sports a white feather plume which I have never seen in photographs, only the white yak or horse hair. Mark, to me your helmet looks like that worn by the Cavalry Colonel in Gala Dress according to the illustration. However, I wonder then, with the German army for comparison, if these helmets may have been worn by generals serving "a la suite" as colonels with bodyguard, cavalry, and other regiments as well? Either way that is a very rare helmet. Both Henry and Arran have posted helmets with black plumes, cruciform spike bases, fluted spike and square visors that Henry identifies as a general in half-dress helmet even though generals are only shown wearing white feather plumes in the 1906 illustrations. On the other hand, I note that the uniform regulations do show a helmet with a black feather plume labeled "chiefs and officials" which refer to individuals holding political appointments with military rank? Interpretation depends on how we translate jefes and officiales. Does that mean generals? The army at large was still issued with the French style shako at this time with a plan for phasing in the pickelhaube for general issue within ten years. This never happened because of the outbreak of the Revolution.