A bottle connector for use in a medical fluid transfer arrangement, the bottle connector having an axial direction and a radial direction and comprising a first part and a second part, the first part comprising a hollow piercing member comprising an inner gas channel and extending in the axial direction beyond the end of the first part. The second part comprises a bottle coupling member, for coupling the bottle connector to a medical bottle. The first and second parts are pre-connected and are concentrically arranged with respect to each other and the bottle connector has a transport configuration with a first, maximum length in which the piercing member is completely located within the bottle connector, and a fluid transfer configuration with a second, minimum length.
