The Bain break insulator was probably designed by Foree Bain in 1890, but no patent has been located since he was much more interested in other things rather than insignificant items such as an insulator. None have any markings. The largest one (white) is 2" x 1-3/4". http://reference.insulators.info/publications/view/?id=5414 [id=450955570] The Bain break and CD 144 were marketed by Central Electric Co. The Bain break insulator became Standard Porcelain No. 35 and was produced by the R. Thomas & Sons Co. as late as the 1920's. Since this style was a Standard Porcelain style, they were probably made by other companies as well. However, these three appear to be Thomas. These three were probably made of high quality dry pressed porcelain due to the complexity of the design, but there are no visible mold lines and the chips do not reveal obvious indications either.