These three insulators are U-151A. We think they were made by D&S in the early 1910's. Only the one in the middle, with black and tan glaze, has an embossed circle in the top of the pinhole. The two others do not. While most U-151A's I've seen had a black glaze with some tan mottling, the one on the right is rust colored with some mustard and the one on the left is a dark brown almost black glaze. [id=176814320] [id=176813593]