I don't know the model but it looks much like the !5xx models, including a magnesium case.
That means it came out before Tandy took Grid over. It likely used the Grid-DOS operating system. It's also likely equvalent to the Grid Compass but without the Bubble memory. A medial Grid product generally referred to as a Grid-case. The tip-off is the size of the external FDD connector in the GridCase, which is larger than than an ordinary PP socket, but is smaller than a SCSI socket. I have a massive 5.25 Grid fdd, which I had always assumed was a SCSI fdd untill searchng on the GRID-site, as well as the forum, brought this to my knowledge
Lawrence