Penetrable membrane structure and coupler incorporating the same in a fluid path

An insert configured to be coupled to a coupling device, the insert comprising:

• an insert body including a first end and a second end and defining a flow passage therethrough, the first end including a fitment structure;
• and
• a penetrable membrane coupled at an opening defined at the second end of the insert body, the penetrable membrane being configured to seal the opening and to be punctured by the coupling device to allow flow through a fluid path between the insert and the coupling device, wherein the penetrable membrane includes:
• a body having a first face and an opposite second face, one of the first and second faces including at least one major portion and at least one minor portion, the major portion including a major thickness, defined between the first and second faces, that is greater than a minor thickness of the minor portion, and the minor portion forming a channel transversely extending into one of the first or second faces, the channel of the minor portion including sidewalls each adjacent to the major portion;
• wherein the sidewalls extend toward each other in a converging configuration.