The A&J MicroDrive System-100 is a tape drive almost identical to the Exatron Stringy Floppy.

Entrepo / A&J MicroDrive was a company that spun off from Exatron. Initially they sold tape drives with the same drive mechanisms and cassettes (called "wafers") as the Exatron Stringy Floppy, then switched to a different drive mechanism from BSR and "microwafer" cassette that is conceptually and essentially the same as the StringyFloppy, merely with slightly different dimensions. The BSR & Exatron drives & wafers are not compatible with each other.

The same drive was sold in at least a few other products for other platforms. Some examples:

Rotronics WafaDrive for the ZX Spectrum
Entrepo Quick Data Drive Model 8500 for Commodor 64 (also rebadged by NCS)

The wafers were made & sold by Entrepo, and also rebadged by at least Phonemark and Smith Corona.

Manual

Manual for the Commodore64 version:
Entrepo Quick Data Drive Model 8500 (to download, ignore the .pdf, get the .cbz)

Software

The "tape operating system" software was distributed from their BBS. Customers were instructed to dial the BBS and download the software and create their own tape backups.
Software for TRS-80 Model 100/102 and TANDY model 200 existed but isn't archived anywhere currently.