The Samsung SCX 3405FW is a bare-bones monochrome laser ... and maximum resolution of 4,800 x 4,800 dpi with interpolation. Features include a 40-page auto-feeder and scan-to-PC function.

I'd wager that's the design brief given to Samsung ... SCX-4500 can not only print at that speed but copy, at resolutions up to 600 x 600 dpi, while scans are completed at up to 600 x 2,400 dpi ...