The Epson DS-32000 Pickup Roller is a crucial, high-volume consumable part for the Epson WorkForce DS-32000 and DS-30000 large-format document scanners.
The specific part number you provided, B12B819621, is one of the component parts within the larger roller maintenance system for this scanner.
The Pickup Roller is the first roller to engage the documents placed in the Automatic Document Feeder (ADF).
The roller's rubber surface must maintain high friction to reliably pull documents of various weights and sizes (up to A3/Ledger format) into the scanner at the DS-32000's high speed.