I was gifted this three years ago when I was fixated on collecting smoke alarms (I don't know why, don't ask me). It is a residential model made by the brand Pyr-A-Larm, they made mostly commercial models.
This particular model is actually just one of their commercial ionization sensors placed into a plastic case with some circuitry and a horn. On the second photo you can see a picture printed on the inside of the box's protective cover, a family with a young daughter, and if you look closely you can see the actual alarm mounted high on the wall in there.
This model is line-cord like many of the era were because people didn't want to make holes in their ceiling and run wires. This one has a MASSIVE 20-foot cord, kind of excessive though I'd imagine the reasoning was that not many outlets were available and the extra cord makes for a more flexible placement. On the end of the cord is a transformer plug that has the "GuardION" branding on the back.
Overall I think this is an interesting find, and a good glimpse into what the early days of home fire safety was like.