Automatic gripping device with extremely flexible hooks

A bag of flexible material, comprising an opening, the bag comprising a device for closing the opening of the automatically gripping hook-in-hook type, comprising a first element having hooks and a second element having hooks, the hooks of the two elements engaging with each other in order to bring about the closure of the opening, at least the first element having hooks comprising a base strip and at least one row of hooks produced from the strip, characterised in that:

• each hook of the first element is delimited over the entire height thereof, from the base strip as far as the top thereof, by two mutually opposed planar surfaces which are transverse relative to the direction of the at least one row of hooks;
• each hook comprises two right and left projection-like engagement portions which project laterally from a shank, extending in a transverse direction relative to the direction of the row and in opposite right and left directions;
• each hook has a thickness (e) corresponding to the distance in the direction of the at least one row of hooks between the two mutually opposed, planar surfaces in the region of the base strip;
• and
• the spacing distance (d) between two successive hooks of the at least one row, measured in the region of the base strip in the direction of the at least one row, or longitudinal direction, is greater than the thickness of each hook.