The present invention relates to a drug delivery (5) comprising a housing (10) with a proximal end (28) and a distal end (22), a cartridge holder (14) adapted to retain a cartridge, the cartridge holder (14) being secured to the housing (10) and having an at least partially transparent side wall, and a cap (40) being capable of covering the distal end (22) of the drug delivery device, being rotationally fixed with respect to the housing (10) and comprising a window aperture (44), the window aperture (44) being capable of displaying information revealed by the cartridge holder (14). Furthermore, using a cap (40) for covering the distal end (22) of the drug delivery device (5) is disclosed.