Pilgrim fired this volley in newsilgrim-
:

I have a blade I purchased years ago for my 7 1/4 Skill. It looks like
a
diamond blade,but isn't. It has approx 5/8" deep slots every 30 deg.or
so. It works great for all types of sheet metal products. It's not
around now or I would try and see the mfg.

It's a "ferrous metal cutting blade". It's nothing more than a circle of
High Speed Steel with some notches. I have a couple.

They cut by friction, alone, and work fine, so long as you're not trying
to preserve a finish, or avoid burrs on the cut line (which they leave in
abundance).

LLoyd