The present invention relates to a delivery member attachment device (10) comprising a neck (12) having an inner space intended to accommodate a connection part of a medicament container, which neck (12) is intended to receive a delivery member (30) for creating a passage between the medicament container via the connection part and through the delivery member, that said neck (12) is arranged with threads (14) arranged to engage with corresponding threads (34) of an attachment part (32 of said delivery member (30), and wherein said neck (12) further is arranged with a number of slits (16) providing a number of tongues (18) between said slits, and wherein said tongues (18) are arranged to flex inwards, when a delivery member (30) is to be attached, to allow an axial pushing of said attachment part (32) onto, and in engagement with, said neck (12).
