The present invention is directed to a pen-type injector equipped with a cartridge holder (1) for a drug delivery device. The cartridge holder has a longitudinal axis and comprises a body (5) for receiving a cartridge, wherein the body (5) comprises at a proximal end (6) engagement means (8) for releasably coupling the cartridge holder (1) to the drug delivery device (2, 3), a latch member (11) for releasably engaging a cap (4) of the drug delivery device and an alignment element (11； 14) which is visual from the outer side of the body (5). The alignment element may be an aperture (14) provided in the body (5) and/or a lug (11) which forms the latch member.
