A cap comprises an opening indicating element provided with a flap arrangement suitable for interacting with an abutment arrangement associated with a neck of a container, said flap arrangement comprising at least one first portion and at least one second portion arranged alongside one another along a peripheral edge of said opening indicating element, a dimension of said at least one second portion measured transversely in relation to said peripheral edge being greater than a corresponding dimension of said at least one first portion measured transversely in relation to said peripheral edge; a container comprises a neck from which an abutment arrangement projects and a cap provided with a flap arrangement suitable for interacting with said abutment arrangement, said abutment arrangement comprising a plurality of distinct abutment elements and said flap arrangement comprising at least one portion suitable for being received in a gap defined between two abutment elements of said plurality of abutment elements.