These printers use the W2011X cartridge:
Click On a Printer to View it's Cartridges
          HP Color LaserJet Enterprise M-856 DN
          HP Color LaserJet Enterprise M-856 X
          HP COLOR LASERJET ENTERPRISE FLOW MFP M-776 Z
          HP COLOR LASERJET ENTERPRISE FLOW MFP M-776 ZS
          HP COLOR LASERJET ENTERPRISE MFP M-776 DN