A coupling member for a closed fluid transfer system includes a housing having a fluid connection and a coupling side. The housing includes a longitudinal axis extending from the fluid connection toward the coupling side and a spike having a fluid opening. The fluid opening is arranged in an end portion of the spike facing the coupling side. A sealing member receptacle is arranged in the housing on the coupling side, and a sealing member is arranged in the sealing member receptacle. The housing includes a housing portion that at least partially surrounds the sealing member receptacle and a threaded portion. The coupling housing with the sealing member is guided by a guiding structure and movable in the direction of the longitudinal axis via the threaded portion between a position with maximum distance to the fluid connection and a position with minimum distance to the fluid connection.