HP RM2-1356-000CN Black cartridge rail assembly is a printer service part identified for supporting the black cartridge rail in compatible HP printer assemblies.
The service manual lists this part for the Color LaserJet Enterprise M751 and Managed E75245, as well as the M856, E85055 and Enterprise MFP M776 printer assemblies. It is specifically designated as the black cartridge rail assembly, distinguishing it from other cartridge rail parts in those printer families.