Two strip materials used for forming fasteners

Two strip materials from which lengths may be severed to form portions of a fastener, said strip materials each having a known structure comprising a polymeric bonding layer;

• and a multiplicity of flexible, resilient, generally U-shaped monofilaments, each monofilament including a central bight portion embedded in the bonding layer, two stem portions extending from the opposire ends of said bight portion and projecting generally normal to an exposed major surface of the bonding layer, and enlarged, generally circular heads at the ends of said stem portions opposite said bight portion, each of the heads having a cam surface opposite its supporting stem portion adapted for engagement with the cam surfaces of heads along the other strip material to produce deflection of the stem portions and to afford movement of the heads on the stem portions past each other, and having a latching surface opposite said cam surface adapted to engage a similar latching surface on another head;
• the bight portions of said U-shaped monofilaments on each strip material being disposed in a rectangular array and spaced to afford movement of the heads of the strip materials past and into releasable engagement with each other, said strip materials being improved to restrict relative movement between the engaged portions in directions parallel to said bonding layers in that the stem portions on each of the strip materials are about equally spaced in each direction to provide numbers of stem portions per unit length on one strip material that are different from and not a multiple of or evenly divisible by the number of stem portions per unit length on the other strip material in either direction so that when portions of the strip materials are engaged with the rows aligned, certain of the stem portions will always interfere with each other to restrict said relative movement between the portions of the strip materials.