http://www.ebay.com/itm/251110295055 looks to me like a prototype cartridge for the IBM 0341 Four-Inch Diskette Drive (aka 3.9-inch) which was announced by IBM in 1983 but shortly thereafter withdrawn in favor of the MIC (Microfloppy Industry Consortium) adaptation of the Sony 3.5-inch design. I don't think any production units ever shipped but evaluation units may have shipped. FWIW, it was a single sided 358 kilobyte FM zone recorded device. The media spec is at bitsavers and promotional material is at the CHM. I have a drive photo in my files Tom