a tenter clip is provided for gripping a web of thermoplastic film between the curved surface of a toggle arm and an anvil surface which is tapered at each of its ends . the surface configurations of the toggle arm and anvil define effective surfaces for gripping the film while allowing the film to stretch under these surfaces . beads are formed at the edges of the web during stretching . these beads wedge into substantially v - shaped gripping regions defined by the toggle arm and anvil to assist in the stretching operation .