A cap (120) for a drug delivery device (1) having a distal end (121) and a proximal end (122)； the cap (120) having an opening at the proximal end and further comprising an outer cap element (130) and an inner cap element (131) being located inside the outer cap element (130), the inner cap element (131) comprising a deformable region (151) and a cap snap means (149)； wherein the deformable region (151) of the inner cap element (131) is deformable into a gap (143) between the inner cap element (131) and the outer cap element (130).
