MTI took a stock TRS-80 Model III, added a few high-performance options, and (with later versions) painted the case white to create the Mod III Plus Series.
Microcomputer Technology Mod III Plus Series (1982, desktop)
Original Retail Price: $2,495 to $4,999
Base Configuration: 4MHz Z80A CPU, Dosplus 4.0, 48K RAM, 5.25-inch floppy disk drive, integral monochrome CRT, integral keyboard/keypad, RS-232 port, application suite, anti-glare screen
Important Options: CP/M 2.2, second 5.25-inch floppy disk drive, 5- or 8MB hard disk drive, printer