Model 1891 Preußen Infantry Regt 83
 
Model 1891 Preußen Mannschaften (Other Ranks) Pickelhaube for Infanterie-Regt. von Wittich (3.Kurhessisches) Nr.83 (Cassel; III Bn Arolsen) XI Armee Korps.

An AKO of 08 January 1891 introduced the Model 1891 Pickelhaube which attempted to address the shortcomings of the Model 1887.

The M1891 was reduced in height but retained the spike, base, rear spine and liner of the M1887. Brass or silver front visor trim was added as well as two new features: a reduced size eagle Wappen and an ingenious system of securing a new design of leather chinstrap on side mounts. Note that prior to 1897, only a single Kokarde was worn on the right side (as worn). The left side had no Kokarde.

As older helmets were constantly modified and updated in the German confederation, it is very unusual to find a surviving original M1891 that has not been modified to an M1895 or M1915.
A view of the M1891 reduced size Wappen (front plate) for line Regiments. The eagle Wappen was reduced in size to 115mm and obtained a more refined shape. For the first time, the gap between the wings and the legs was now voided. Like it's predecessors, the M1891 utilized threaded bolts on the reverse to secure it to the helmet shell with internal brass nuts.
 
The rear spine of the M1891 remained unchanged from the M1871 and M1887 helmets with no air vent.
A view of the spike and base on a M1891 helmet. On M1891 helmets, the spike is considerably shorter than the M1871. This change occurred on the M1887 helmet.
Like earlier models, the neck of the spike rotates to close the vent holes. This was a standard feature until 1895.
The Model 1891 introduced a new leather chinstrap with double sliding buckles with brass loops at each end with a cut "V". The chinstrap loop was designed to fit onto the corresponding post, keeping it secure but allowing easy removal.

The M1891 post is longer and sturdier when compared to the posts on the Model 1895 which followed.
1891 brought about a final reduction in the height of the helmet, giving it a more domed appearance although the front and rear visors are quite large; an influence from the M1871 and M1887 Pickelhaube. The helmet leather overall is very thick resulting in a much heavier and robust helmet when compared to following helmets like the Model 1895.
The liner of this M1891 example is made from the standard heavy leather with 'fingers' for a cord to adjust the fit.
 
The helmet is unit marked in white paint on the interior to "83. R." and dated 1891.

Could there be any better date on a M1891?
 
A view of the front interior showing the brass nuts that hold the Wappen on.