This AC-E19N AC Power Adapter from Canon is compatible with the EOS-1D X Mark III DSLR, and is used with the general purpose DC coupler DR-E19 to provide a constant power supply when shooting indoors.
★★★★★ Perfect for long indoor shoots! The AC-E19N paired with the DR-E19 keeps my EOS-1D X Mark III powered continuously, so I never worry about batteries dying. Solid Canon quality and exactly as described.