The Teac FD-55GFR is the most capable drive in the Teac FD-55 series, able to read disks written by all other models in the series, and write to many of them as well. It can read and write double-sided high-density 80-track (1.2MB) disks, as well as reading double-sided double-density 40-track (360kB) disks. It is also capable of reading the older single-sided double-density 40-track (160/180kB) format as well, used by the earliest versions of DOS.
Being an 80-track drive however, it still suffers from the same problems as any other when writing to 40-track (double-density) disks.
The GFR suffix indicates the drive combines functionality of the G (high-density) and F (double-density) models, with R referring to a refresh, where the design was refined to reduce manufacturing cost and power consumption.