Ludwig Baer wrote that interwar commercial M18 ear cut outs were produced, and I think you are right that he said they were in a size 66. I think he had a picture of one in the 3 volume German language treatise, I just can't my copy of it at the moment. I have never seen a real one of those in over 50 years of collecting, but the one in the picture in Baer's book certainly looked good. If I recall correctly, it also had the head of a chin strap rivet on the exterior, at or near the break between the apron and the dome, not unlike the later so called Himmler style helmets. If I can find the book I will post the picture on this thread later today. Regarding WWI vintage ear cut outs, ALL were ET 64's, with stepped lugs. Jim G.