A coupling device that provides a first medical device with a fluid port, said coupling device comprising at least one connection site that receives and connects a second medical device, a piercing member having a longitudinal axis A, a piercing tip portion and a piercing tip, said piercing member being arranged in fluid communication with said at least one connection site and adapted to pierce a membrane on said first medical device that provides said first medical device with said fluid port, an outer portion of the piercing member being tapered in a direction towards an end of the piercing tip; said piercing member comprises a first fluid channel and a second fluid channel, said first fluid channel and second fluid channels having a first opening at said piercing tip portion, wherein said first fluid channel and second fluid channels are separated by a fluid channel separation wall, said fluid channel separation wall having a convex surface portion, with respect to said longitudinal axis A, said convex surface portion faces said first fluid channel at said piercing tip portion, wherein said first fluid channel is defined by said fluid channel separation wall and an opposing first outer wall, and in that said second fluid channel is defined by said fluid channel separation wall and an opposing second outer wall, said first opening of said first fluid channel has a first cut surface having a rim on said opposing first outer wall, and said first opening of said second fluid channel has a second cut surface defined by a rim of said opposing second outer wall, the first and second cut surfaces being adapted to pierce said membrane, the rim of the first fluid channel transcends to the separation wall and the rim of the second fluid channel transcends to the piercing tip; said fluid channel separation wall further comprises a concave portion, with respect to said longitudinal axis, said concave portion facing said second fluid channel at said piercing tip portion, wherein said concave portion extends the fully along said fluid channel separation wall; the distance of the crest of the rim of the first fluid channel to the piercing tip is between 6-15 mm. and the distance of the crest of the rim of the second fluid channel to the piercing tip is between 3-5 mm. at least one connection site that receives and connects a second medical device, a piercing member having a longitudinal axis A, a piercing tip portion and a piercing tip, said piercing member being arranged in fluid communication with said at least one connection site and adapted to pierce a membrane on said first medical device that provides said first medical device with said fluid port, an outer portion of the piercing member being tapered in a direction towards an end of the piercing tip; said piercing member comprises a first fluid channel and a second fluid channel, said first fluid channel and second fluid channels having a first opening at said piercing tip portion, wherein said first fluid channel and second fluid channels are separated by a fluid channel separation wall, said fluid channel separation wall having a convex surface portion, with respect to said longitudinal axis A, said convex surface portion faces said first fluid channel at said piercing tip portion, wherein said first fluid channel is defined by said fluid channel separation wall and an opposing first outer wall, and in that said second fluid channel is defined by said fluid channel separation wall and an opposing second outer wall, said first opening of said first fluid channel has a first cut surface having a rim on said opposing first outer wall, and said first opening of said second fluid channel has a second cut surface defined by a rim of said opposing second outer wall, the first and second cut surfaces being adapted to pierce said membrane, the rim of the first fluid channel transcends to the separation wall and the rim of the second fluid channel transcends to the piercing tip; said fluid channel separation wall further comprises a concave portion, with respect to said longitudinal axis, said concave portion facing said second fluid channel at said piercing tip portion, wherein said concave portion extends the fully along said fluid channel separation wall; the distance of the crest of the rim of the first fluid channel to the piercing tip is between 6-15 mm. and the distance of the crest of the rim of the second fluid channel to the piercing tip is between 3-5 mm.