A cartridge unit for an inkjet printer comprising: a body portion having one or more ink storage compartments; a pagewidth printhead assembly mountable to said body portion and configured to receive ink from the one or more compartments for printing; and a capper unit mountable to said body portion so as to extend along the length of the printhead assembly, the capper unit housing a capping element which is movable with respect to the capper unit to contact a surface of the printhead assembly.