I have/had quite of few of these. They are unique in their frame construction. I call it "Cast in place". Aluminum lugs cast with the steel frame tubes pre-placed in the molds. Head tube is a single casting, bb, seat lug and fork crown. No welding, no brazing other than the fork ends and bridges. Look close and the molds have fake spear points to emulate pointy lugs.
Cast aluminum doesn't tolerate flexing so the seat post is a wedge expander type. Much like an old school handlebar stem. There is a bolt head on the top of the post to loosen up the wedge. The bolt you see in the lug is just for holding the brake cable hanger and reflector in place. Been my experience the seat tube is full of crudy water and other filth. There is no opening into the bb shell so junk collects in the tubes.
They sold a variety of models. The coolest model was the Sub Mariner. That was their high end (relatively speaking) bike that had polished stainless steel main frame tubes. I rebuilt one as a 5 speed for my sister and another girls frame version with a Shimano 333 hub and 27" wheels. Those are still in my mom's garage.
I just dismantled a Super Speed with all steel parts and every steel part was rusty. Steel cottered cranks, steel rims, etc. Must of have been a cheaper model Looks like it had a baby seat on it and the seat stays got slightly bent. Cool handle bars but they had some chrome flaking off. Surely not triple plate chrome. Aluminum peg as a der protector. And a wicked head badge. I kept the frame set. Might make an okay ss/fixie project.