The Brother DSmobile 920DW ($199.99 direct) scanner is basically a slightly heavier-duty version of the Brother DSmobile 820W. It offers the same ability to scan either to a PC or to an SD card with no PC needed; the same Wi-Fi support to let you connect from a smartphone or tablet to see the scans you saved to memory; and the same set of software. What it adds is duplex (two-sided) scanning with only a little extra size and weight and a little higher cost. If you need to scan duplex documents even occasionally, that makes it the obviously better choice. The DS-920DW's($169.99 at Amazon) ability to scan with or without a PC gives it a claim on being in competition both with portable scanners that scan to a PC and those that don't. As I suggested in my review of the Brother DS-820W, however, both Brother models are at least arguably more directly competitive with models that can scan without a PC, and particularly those few that let you view the scans on a smartphone or tablet aft...
The Brother DSmobile 920DW offers duplex, manual feed scanning with or without a computer and can connect by Wi-Fi to let you see scanned documents on your smartphone or tablet.
Portable; Duplexes; Scans with or without a computer; Connects by Wi-Fi, letting you see scans on your smartphone
Doesn't do a good job with business cards or expense receipts