Model train parts Single-arm pantograph, set of 2 Base bottom hole (square) size: 13 x 12mm I cannot determine if this size is for HO gauge. This item is being sold as part of the estate of a family member who was a model train collector and enthusiast. Please make your judgment based on the images. Be sure to check the images. The parts are only in a plastic bag, and the manufacturer's name is unknown. They were stored in a plastic case that had a different product name written on it. The seller will likely be unable to answer questions. Please understand that these items have been stored at home, and purchase only if you agree to this. I have confirmed the product name with an acquaintance. Returns are not accepted, so please purchase only if you understand this.