The present disclosure relates to a drug delivery device for setting and injecting of a dose of an injectable medicament, the drug delivery device comprising: an elongated housing extending along a longitudinal axis and having a sidewall with at least a first aperture, at least one number sleeve rotatably supported inside the housing and comprising an outer surface, wherein a first portion of the outer surface is visible through the first aperture and wherein the number sleeve comprises a non-visible code in the region of the first portion.