Way back, at least where I was, most people called them a 'Sven Saw'. There was a larger bow version that was quite capable and a small and lighter folding triangular looking unit that was popular with campers and trail clearing crews. Folded you had a single aluminum bar with all the pieces or the frame and the blade stored inside.
Good product. Haven't seen one in a few years.
Still available:
www.svensaw.com/I carry a retractable saw in my pack, but in my truck I prefer the 21" non-folding tubular frame with the triangular shape. When I pack for the woods, I carry a larger bow saw as well.