It has double Bekleidungsamt markings. "B.A.IV" and "_.A.XVIII". That is somewhat unusual. Normally, when there are two corps markings, the later one is a "B.J.A." (Bekleidungs-Instandsetzungs-Amt) marking that indicates that the helmet was repaired by a corps other than the original issuing one.
Since the XVIII corps marking is incomplete, it is possible that the marking was "B.J.A." rather than "B.A.". That would make more sense.