Many thanks to Malcolm of the “Peterborough Linux Users Group” for the Rotronics Wafadrive for the ZX Spectrum! Will give it a ‘spin’ in the next couple of days.
Here is what Wikipedia has to say about it…
The drives could run at two speeds, high speed for seeking and low speed for reading/writing, which was significantly slower than that of Microdrives. The cartridges (or “wafers”), the same as those used in Entrepo stringy floppy devices for other microcomputers, were physically larger than Microdrive cartridges. They were available in three different capacities, nominally 16 kB, 64 kB or 128 kB.
The same drive mechanism, manufactured by BSR, and cartridges were used in a similar device known as the Quick Data Drive (QDD), designed to connect to the serial port of the Commodore 64 home computer.