Recently I received these new signals and noticed that they also were fire rested on both skirt and petticoat. Unfortunately they weren't the same style as the 3 blue signals. I thumbed through all the books I have hoping to find any mention on insulators double rested like these 5. No such luck. Then I thought of checking Elton Gish's porcelain guide (wonderful "must have" book) and cross checking the two styles (U-268 and U-263) to see if any manufacturers were credited with making these. Lo' and behold the only manufacturer listed was Triangle M (an Illinois Electric Porcelain Company marking used after their "Macomb" mark and before marking with "Illinois", TriM markings date from 1915 to circa 1927). So flashlight and magnifying glass in hand I found TriM markings on these two signals and one very faint marking on one of the blues (I originally thought a second blue had a faint marking also, but it is so very faint I'm not calling it "marked" anymore). But wait . . . there's more