The insulator on the left is the Brookfield style with the narrow dome. The center insulator is the Brookfield style with the wide dome. The insulator on the right is the F M Locke style. Please note that the wide dome Brookfield sits flat on its outer skirt. The F M Locke example does sit on the inner skirt. This insulator was on display at Springfield along with another example. In talking with the owner of the other example we felt that these were the only 2 examples of this insulator known in the hobby.