This one is more than likely "brushed aluminum". Narragansett Electric used these before NGrid took over in the mid-to-late 90's. National Grid has installed a few tapered E arms before, but they've been the 6ft kind.

my vote is Aluminum also.

I'd say aluminium too, it looks a lot like the aluminium ones in my area.

Looks like this could be a HAPCO arm?

Just a little late, I'd say this is aluminum as well, it looks like many of our aluminum arms after they have been outside for 40 years.

Does not look like am HAPCO arm......the mounting bracket looks a lot more like its made by Curlee

What do HAPCO mounts look like? I guess the tapered E arms here aren't made by HAPCO then since they have this style mounting bracket.

Curlee style note the 3 screw mount? and how the screws mounts on the sides in the bottom

HAPCO uses 2 bolts on the bracket area, but I really can't find a good clear picture of it but look at page 102 on this link

Shakespeare arms are similar to above but the bracket has some grooves like my shakespeare arm seen here Here are the design from their page and we have those arms on the fiberglass poles all over my area under BGE!!! See them right here!

Utility Metals arm and bracket their tapered arm seem more rounded than the Shakespeare style....

There are other brands too....but some seem to be hard to find online or some places.....I need to ask about my other arm, it may be Maclean...not sure...will need to ask...

Ahh. I looked at the other arms in the pdf too and they all match up with the arms here.