Epson Workforce Pro GT-S85 A4 Colour Duplex Pass-Through Scanner - USB - J271A

These units are refurbished throughout with perfect scan output.  6 months RTB warranty.

This is what Epson has to say: -

Key Features
High-speed scans: Up to 40ppm/80ipm in simplex/duplex
Ultrasonic sensor: Detect & easily recover paper jams
Scan large jobs: 75-sheet automatic document feeder
Two-sided scanning: Scan both sides in a single pass
Easy integration: Compatible with leading IT systems

High-quality productivity: The GT-S85 produces high-quality scans at speeds of up to 40 pages per minute in simplex or 80 images per minute in duplex, in mono and colour, at 200dpi. Double-sided pages are scanned in a single pass, while a 75-sheet automatic document feeder is perfect for large-volume jobs.