The Brother DS-720D is a color duplex roll scanner with Letter maximum paper width. It works with Linux using binary-only SANE backend files. I mirrored them here in case they become unavailable sometime in the future together with the scanner docs:

Quick Start Guide User Manual

libsane-dsseries1.0.5-1amd64.deb

libsane-dsseries1.0.5-1i386.deb

libsane-dsseries-1.0.5-1.i586.rpm

libsane-dsseries-1.0.5-1.x8664.rpm

History of this item:

Timestamp Event
2015-11-01 Purchased on http://www.x-kom.pl/ for 569 PLN