ITT-DOS is an enhanced version of MS-DOS. ITT was a conglomerate that decided to add PC manufacturing to its portfolio. The XTRA line was considered good quality. One distinguishing feature was the optional black mouse, which had three slanted rectangular buttons.

ITT Xtra Personal Computer (May 1984, desktop PC)
Original Retail Price: $2,499 to $6,399
Base Configuration: 8088 CPU, ITT-DOS 2.0, five ISA slots, 128K RAM (640K max), 32K ROM, 5.25-inch floppy disk drive, keyboard/keypad, RS-232C and parallel ports, MS-DOS manuals
Video: 25-line x 80-column text
Size/Weight: 5.6 x 14 x 15.6 inches, 21.5 lbs.
Important Options: MS-DOS 2.11 or CP/M-86, second 5.25-inch floppy disk drive, 10- or 20MB hard disk drive, 12-inch color or 14-inch monochrome monitor, CGA or monochrome card, mouse