The shell (50) is intended to receive an injection system comprising a syringe received in a safety device (103) which has: - a body (20) receiving the syringe； - a shield (30) movable relative to the body, for covering a needle； - finger flanges (31) extending outwardly. The shell comprises a tubular housing (51) receiving a distal portion of the safety device (103), and a casing (52) receiving the finger flange (31) and comprising: - several snap features (60) which flex outwardly during insertion of the finger flange in the casing, the finger flange being inserted distally from a distal face (61) of the snap feature in the mounted position； - a protrusion (70) located distally from each distal face (61), which exerts an inward biasing force on the finger flange in the mounted position.
