This yellow color porcelain power insulator looks like a U-503 to me. It is embossed "PP" on the tip of the cable top. It measures 3 3/4" wide by 3 3/4" tall. The insulator is in very near mint condition with only a tiny 3/16" flake off the under edge of the cable top. A very nice looking yellow color. Priced at $25.00 plus shipping. Payment by PayPal Friends mode or check.