I do not collect porcelain insulators but when I saw this piece in a recent auction I had to have it. The piece was made in Russia and its u number is U-1321A. The insulator has the number 24 on side of the dome. It is designed and looks like CD 154 which is what I collect. Compared to the other U-1321A from other countries this Russian piece looks the most like a CD 154. The Chilean and Columbian examples look more like CD 155 with the thick lower wire ridge. After 24 years I have some "mud" in my collection.