A microphone with a bi-directional polar pattern. See Polar Pattern, Bi-directional.
"Just received my order for the restored Record-Gram recording that my husband made in 1951 while he was stationed in the Marine Corps at Camp Pendleton, CA before being shipped out to Korea. He sent the recording back to his family in Hawaii and it was not in the best of shape when we retrieved it in the 1980's. After several years, I checked ..."