To solve the problem of the fear of inadequacy of armor protection on the already heavily armored KV-1 Model 1941, It was decided to bring the armor protection of the turret up to a thickness to 75mm.

Since the capability of producing such a thick armor plate was lacking at the time, so an interim solution was to use bolt on armor, 25mm of thickness, bolt directly to the outside of the turret and some other parts of the hull. This type was usually referred to as KV-1s Ehkranami.