Over the past few months I picked up some interesting insulators. You might recognize two of these from the Icon for sale pages. I had one in my collection and was glad to get the other two. The large one has no markings but the two smaller are marked with two different markings, D. L. Co. 6 which stands for Duquesne Light Co. of Pittsburgh, PA. These were sold by J.H. Parker and a few other jobbers in the late teens early twentys. There is one patent for this design USD49365S by Henrey N. Muller of Pittsburg, PA. on July 11, 1916. I assume the ridges were for drainage and to lessen breakage. Like my three they have several chips and flakes. I would love to know if there are any spools, knobs or wire holders marked D. L. Co. or did they just specifically have this strain made for them. Either way it's a future mystery and a very neat item.