This is a German laundry bleach called "Henko" or "Henkel's Bleich-Soda" (Henkel's bleaching soda), produced during the 3rd Reich. The box shows the price in the Reichs Pfenning. The box is full, did not open, from the warehouse unused inventory.
Such powder was supplied to the Wehrmacht troops under military contracts. The packaging says "Einweich-und Enthärtungs-Mittel" (water soaking and softening agent) marked "Ohne Chlor" (chlorine-free). The product was produced by Henkel from Dusseldorf, which still exists today and is known for its detergents.