a closure device for joining two surfaces , which is easily engageable and disengageable but provides a firm lock when closed , comprises two substrates , one of the substrates having a plurality of expandable and contractible openings which lie in the plane of the one substrate and the other one of the substrates having a corresponding plurality of fasteners , each comprising a stem attached at one of its ends to the other substrate and extending away from the surface thereof , the free end of the stem having an enlarged locking head having dimensions which are larger than the dimensions of the openings when contracted but sufficiently small to freely pass through the openings when expanded . the stem may also be provided with a plurality of locking projections along its length in order to assist or to replace the locking action of the locking head .