Founded in 1954 as TMP INc. Made rubber electrical products for various companies. Changed name to Advanced Rubber Products in 1994. Started a line of rubber & silicon insulators for the U.S. and foriegn markets includuing Cooper Power Systems, G&W electric and others in 2004. Products copied Victor insulator styles of ANSI pin type and Line Post styles. Here is a picture of the ANSI style 55-5. Marked on the front skirt ARP/SKPI-55-5. Rear has clock face with 1/arrow pointing to 7 and 12. Measures 5"h X 7"w. I have yet to figure out the code for production but I assume it is the hour, quarter and date.