Wow, that's an... interesting, find. Hopefully you at least have an Amdek Amdisk 3" to display alongside it.
I remember they made just enough of those things for them to find their way to the various electronics surplus dealers, IE, searching Google Books finds an ad in a 1987 issue of Popular Science from "American Design Components" in which they're selling off both bare drives and "kits" for interfacing the drives to IBM PCs, Apple IIs, and... IBM PCjrs. I wonder how many units of these were actually made. It appears they hit the market around late 1982, and they must of been sold up to around 1985 to have ended up inside a PCjr expansion, but there's practically nothing about them to be found online other than some timeline entries and claims that the disk format was actually invented by Dysan. (Which did so because they thought the market needed a "microfloppy" format whose disks didn't require the existing makers of 8" and 5.25" disks to extensively retool their factories.)
I remember they made just enough of those things for them to find their way to the various electronics surplus dealers, IE, searching Google Books finds an ad in a 1987 issue of Popular Science from "American Design Components" in which they're selling off both bare drives and "kits" for interfacing the drives to IBM PCs, Apple IIs, and... IBM PCjrs. I wonder how many units of these were actually made. It appears they hit the market around late 1982, and they must of been sold up to around 1985 to have ended up inside a PCjr expansion, but there's practically nothing about them to be found online other than some timeline entries and claims that the disk format was actually invented by Dysan. (Which did so because they thought the market needed a "microfloppy" format whose disks didn't require the existing makers of 8" and 5.25" disks to extensively retool their factories.)