Probably a little explanation is in order. This insulator is marked FCAB, which stands for the Ferro Carril Antofagasta y Bolivia, which translates to the Antofagasta and Bolivia Railroad. Antofagasta is a city in northern Chile. The railroad is narrow gauge. This is very probably the only railroad marked insulator which can be found in the identical shape in three different materials - glass, porcelain and this black composite material. This insulator is 3 1/4" tall, with an inner skirt and smaller than US threads. $65 postpaid.