Here are four fire alarm insulators, the usual HG 133s, and what might be a later replacement, or a swap out by a collector long ago. I do not know know. I have found an Armstrong CD 115 on the lines, and there are a few places where Hemingray 45s and even an H.K. Porter can be found. This pole also shows where open wire once dead ended, and aerial fire alarm cable carried forth. 1/31/2010.