With a Rolleinar 1 on an 80 mm lens the effective focal length becomes 72 mm, which allows a focussing distance of 45 cm to 1 m (18½" to 39½").
The 1, 2 and 3 Rolleinars come in two parts: one part for the viewing lens and one part for the taking lens. The deeper of the two parts is for the viewing lens: it includes a prism for parallax correction.
The optical quality of the Rolleinars is excellent. I have the 0.35, 0.7, 1 and 2, but only in Bay III. I don't think that the 0.35 and 0.7 were available in Bay I or Bay II - could be wrong though.
PS I think that it's a 1954-55-56 sort of model? 'Bout the same age as I am, but I'm no sort of model. See here for an indefinite answer.