This insulator is 5 1/2" tall, 8 1/2" wide at its widest point and 2 1/2" wide at its base. It has a 6 1/4" diameter cast iron insert marked NY M R CO and L 549, fitted into a 1 3/4" threadless pin hole in the top. There is a 2 1/2" pin hole in the base onto which to mount the insulator. It was taken out of service about 1970.