to form sealed delivery passages along which the ink passes en route to each of the ink storage compartments 24 the underside of the lid assembly 21 also includes moulded features or ridges 69 which extend into the ink storage compartments 24 when the lid assembly 21 is sealed to the main body 20 these moulded features or ridges 69 ensure that an air gap is formed above the absorbent material 29 for venting via the vent hole 63 to assist the absorbent material 29 to function to absorb the ink and retain the ink suspended therein under capillary action as shown in fig5 and 60 extending downwardly from the outer surface 60 of the lid assembly 21 are a pair of guide walls 70 the guide walls 70 assist in locating the lid assembly 21 on the main body 20 during assembly the guide walls 70 also have a recessed portion 71 formed therein which acts as a hand grip to assist in handling the cartridge unit during use as shown more clearly in fig5 the guide wall 70 that extends along the face of the main body 20 proximal the printhead assembly 22 also includes a series of holes 72 in a lower edge thereof these holes 72 are arranged to align with and receive the locating studs 38 provided on the main body 20 onto which the flex pcb backer 37 and the flex pcb 52 of the printhead assembly 22 are attached in this arrangement when the lid assembly 21 is fixed to the main body 20 a portion of the flex pcb 52 of the printhead assembly 22 is sandwiched between the guide wall 70 and the flex pcb backer 37 thereby.