Adaptor for a drug delivery device and drug delivery device

A drug delivery device comprising:

• a reservoir and a longitudinal tip, wherein the longitudinal tip has an outer surface and a longitudinal channel for dispensing any material stored into the reservoir;
• and
• an adaptor comprising:
• a distal part that defines a connecting ring, wherein the connecting ring is designed to receive a connector;
• and
• a proximal part that defines a mounting ring, wherein the mounting ring has an inner surface, and wherein the mounting ring is shaped and configured such that, when the adaptor is mounted around the longitudinal tip of the drug delivery device, at least one annular space is created between the inner surface of the mounting ring and an outer surface of the longitudinal tip, the at least one annular space being able to accommodate an adhesive layer in order to bond the adaptor to the longitudinal tip, wherein an annular ring is provided at a distal extremity of the inner surface of the mounting ring, and
• wherein the inner surface of the mounting ring comprises at least one protrusion where, when the adaptor is mounted around the longitudinal tip of the drug delivery device, the at least one protrusion protrudes into the at least one annular space, the at least one protrusion being in the form of transversal segments.