This the CD 187, the smaller of the Brown Ponies. It is patented dated. It is a nice lighter blue. Thread stress crack. The unusual chipping at the opening (the glass had to be broken out on these to be used). These are Duplex Insulators and were used on a duplex pin (a double threaded pin) . A standard insulators, like a pony, was installed on the top and the Browns Pony on the bottom. The pin allowed easy and quick installation of new lines by drilling an existing crossarm and then dropping the pin in the hole. The tapper of the pin prevented the pin from dropping through and yielded two new lines for each pin installed. $23.00 shipped with in the Continental US.