I do not know the specific make of that guide but it is known as a hand mitre saw.
For example, from here:
Appears(The one in that image appears to resemble a vintage Stanley mitre box (well, sort ofvintage Stanley mitre box, will domaybe a better search when not on phone)Stanley 358.)
There are other styles of mitre guides and boxes, too, the most familiar probably being the little plastic box with angled slots in the sides.