Epson ES-50 Carrier Sheet (often referenced by the part number B12B819471 or the global SKU B12B819451) is a key accessory for the Epson WorkForce ES-50 and other portable sheet-fed document scanners in that line (like the ES-60W, DS-70, and DS-80W).
 
The Carrier Sheet is a durable, protective plastic sleeve designed to greatly enhance the versatility of the ES-50's sheet-fed mechanism. Its main purpose is to allow the scanner to handle documents and media that cannot be safely fed directly through the rollers