Infanterie-Regt. Nr.92 Senior NCO Pickelhaube
 
Eigetumsstück (privately purchased) Pickelhaube from Braunschweigisches Infanterie-Regt. Nr.92 (Braunschweig) for an Unteroffizier mit Portepee.

Unteroffizier mit Portepee were the two highest ranks of NCO who were entitled to wear the Officer's sword knot and wear the special Unteroffizier mit Portepee Kokarde with seperate metal ring overlay on the Pickelhaube. The two ranks of Unteroffizier mit Portepee were Feldwebel (Company Sergeant Major / First Sergeant in the US) and Vizefeldwebel (Company Warrant-officer / Master Sergeant in the US).

Each infantry Battalion normally had four Feldwebel (one for each Company) who was the Etatmässiger Feldwebel - 'Der Spiess' who wore the double rows of NCO braid on the cuffs. The Vizefeldwebel wore the single row of NCO lace on the collar and cuffs.
A view of the Braunschweig Wappen (front plate) for Mannschaften (Other Ranks) with Totenkopf with Neusilber (nickel-silver) Totenkopf above "PENINSULA" Bandeau mounted to a Preußen pattern eagle Wappen, with "FUERST" Bandeau on the chest instead of the Preußen "KOENIG" Bandeau. Although the Wappen is high quality and private purchase pattern (screw post retainers) the crown is not voided.
To accommodate a Haarbusch, the tall spike is removable.

This is important, as if there was doubt about the Wappen being original to the helmet, with a removable spike top it would limit the helmet as being from one of the regiments that wore a Preußen Grenadier eagle Wappen or those with a with a smaller State Wappen overlaid on the eagle who were entitled to wear a Haarbusche. Only Grenadier Regts 2 to 9 (with the old Grenadier Wappen), and the other Regts with equally rare Wappen, like IR 91, 93, 94, 95, 96, and 153 would qualify.
Note that the rear spine does not incorporate the M1895 rear sliding air vent, correct for a private purchase pattern helmet.
A view of the 51mm Braunschweig Unteroffizier mit Portepee Kokarde with the additional gilt ring with a distinctive diagonal ribbing; this pattern of Kokarde only worn by Unteroffizier mit Portepee entitled to wear the officer's sword knot.

What make these Kokarden interesting, is that they are not cut to fit the M91 side posts; they are small-hole private-purchase pattern, and the M91 posts have been placed on the outside.
With the Wappen carefully removed, the 'ghost' becomes visible where it has sat for over 90 years.
The liner of this example is of the highest quality available with internal leather sweatband and silk skull-cap.

The underside of the visors, however, are exposed leather, which places this example in the medium-quality range.
The paper tag inside between the nuts for the Wappen reads:

OEKONOMIE (Company name)
Kunstinstitut (art institute)
für galvanische Erneuerung (for electroplating renewal)
Inh. E Lazarus (name of the company owner)
Berlin C. a.d. Spandauerbr. 4-5 (company address)
Kopfweite (helmet size)
Com. Nr. (claim number)
For interest, here are three straps pattern worn by Braunschweigisches Infanterie-Regt. Nr.92.

On the left, the dark blue pattern with black cypher worn on the Braunschweig Polrock (which looked like a Husaren Attila) until 1886 with cord cypher, in the centre the white strap with red chain-stitched and felt cypher cypher worn after Braunschweig adopted the Preußen pattern Waffenrock in 1886, and on the right the M1915 strap worn on the M1915 Bluse.