Head clip secure the tile where the nibs are resting on the batten. Unlike nails or screws, the head clip does not require a hole in the tile, thus giving higher protection against water ingress and limiting the risk of tile breakage.
The effectiveness of head clips against wind uplift depends heavily on the design of the roof tile. In most cases the head clip fixes only the top of the roof tile to the batten while the bottom has almost no resistance against any wind load. For some specific roof tiles the head clip is the ideal solution to secure up to three tiles simultaneously.
Head clips are either nailed into the batten or clamped onto the batten.