HP lists this spare part number for the HP EliteBook 840 G6 Healthcare Edition in its Maintenance and Service Guide (printed p.21).
Source notes
HP Maintenance and Service Guide for the HP EliteBook 840 G6 Healthcare Edition (Document Part Number L65467-001), spare parts table, printed p.21: "use in models without RFID or NFC L64704-001". Read from the cached HP manual (via FDY-MM-015-K5).