Many CD 151 H.G. Co. /Petticoat insulators were used on the Chicago, Rock Island & Pacific Railroad as it ran East and West through Iowa. Most were various aqua and blue aqua colors; however, there were a few that were near clear in color. I also found the CD 151 H.G. Co. /Petticoat in rare colors including ice, cornflower blue and depression green. This post compares the back all three colors found in Iowa. Details are as follows:

CD-151 H.G. Co. (Front Skirt) / Petticoat (Back Skirt) - Medium Cornflower Blue - Measures: 88mm Wide x 104mm Height

CD-151 H.G. Co. (Front Skirt) / Petticoat (Back Skirt) - Ice /Near Clear - Measures: 88mm Wide x 103mm Height

CD-151 H.G. Co. (Front Skirt) / Petticoat (Back Skirt) - Depression Green - Measures: 88mm Wide x 104mm Height