Insulators as follows -- actual postage additional

U-2531 German import to Canada - marked HESCHO on the ear - nice blue-gray glaze - VNM -- $8

U-296 no markings - great drippy gray glaze -- VNM -- $8

U-266A (sim) no markings - awesome blue glaze -- some deep wire rubs, light flaking on the lower wire groove and inside the skirt -- $8

U-294 inkstamp CHANCE in a light blue glaze -- $6

Or take all four for $25