Epson product code B12B819641 refers to a Separation Roller component for the Epson WorkForce DS-32000 (and the related DS-30000) Large-Format Document Scanner.B12B819641 is listed by some distributors, you may more commonly see the official Epson part number B12B819631 for the same Separation Roller unit.
 
Part Name: Separation Roller (or Separation Roller Unit).
Compatibility: Epson WorkForce DS-32000 and DS-30000 (A3/Ledger High-Volume Scanners).
Primary Function: Its most critical function is to ensure single-sheet feeding. It works against the Pickup Roller to apply a calculated friction, holding back all but the top sheet of a document stack.