A teatcup, configured to be attached to the teat of an animal to be milked, and a cartridge for said teatcup, where the cartridge has an elongated sleeve with having an upper end section and a lower end section, and a barrel that is pre-mounted in the elongated sleeve (8) and forming an inner space for receiving the teat such that a pulsation chamber is formed between the elongated sleeve and the barrel, where the cartridge also has a head member at the upper end section with a lip surrounding an opening into the inner space, where the elongated sleeve has a flange extending outwardly at the upper end section, and the head member has a plurality of locking members each configured to grip the flange, each of the locking members extending towards the lower end section and beyond the flange.