A coupling member for a closed fluid transfer system includes a housing having a fluid connection and a coupling side. A first channel extends from the fluid connection toward the coupling side for fluidly connecting the fluid connection and the coupling side. An elastomer member surrounds an opening of the first channel, or forms a second channel adjoining the first channel. An elastomer member opening of the second channel is parallel to the longitudinal axis of the housing. The sealing surface is formed between a first position, in which the sealing surface seals the opening or the elastomer member opening of the second channel, and a second position, in which the sealing surface exposes the opening of the first channel or the elastomer member opening of the second channel for fluid communication with the coupling side.