This yarn was made by Minerva, prior to the merger of Columbia and Minerva in the early 1950s. It is identical to the Columbia-Minerva Zephyr fingering wool yarn from the later 1950s and beyond. The yarn was being used in Minerva pattern books in the mid 1940’s.
It is quite soft, and feels almost like merino.

Its recommended gauge was something like 7-8 st/inch.