Most “Smart Image” drives use the style of tapes also used by the Teac MT-2ST series drives, such at the CT-500H, CT-600H and compatible. They look a lot like standard audio cassette tapes but have a “notch” cut out of the top.
Ad from PC Mag May 31, 1988, pg. 145
PC Mag Oct 14, 1986
“High Density Data Cassette”