This is a particularly different kind of helmet. Information on these helmet seems to be very scarce, with some information coming from Pietsch, some from Kleiteman and some from old copies of the Deutsche Soldaten Jahrbook. This is a private purchase helmet that has been adjusted by collectors over the last 150 years. There was a similar helmet on the Weitze site. The officer's field badge is correct and original, but did not come with this helmet. The chin strap is correct in original, but the method with which it is attached to the helmet is not original. I would have expected this to have had chin scales originally, but apparently Landwehr shako's did not.
The really key issue is that the wappen is made of silver. the outer ring, which in most helmets of this type are painted white were left silver for officers, Feldwebel and Vizefeldwebel. I do not know for certain if this helmet is for an officer or a Feldwebel. But my limited understanding is that the Feldwebel and Vizefeldwebel did not have the officer field badge. I am way open to other opinions and research on this type of helmet.