An injection device configured for attachment to the skin of a patient using an adhesive layer, the injection device comprises a release liner covering the adhesive layer thereby preventing skin attachment. The release liner comprises a sheet of material wherein a first surface contacts the adhesive layer, an aperture defining a passage for a film connected to a first sterile barrier film located within the injection device. Wherein an end of the film is connected to a second surface of the sheet of material that is opposite to the first surface, and the release liner is covered by a strengthening sheet adhesively connected to the second surface and covering the aperture and the end of the film.
