Functioning - The FUR is suitable for push-through installation. - Screwing in the screw causes the individual teeth to expand. In solid materials, the teeth create even expansion forces. In hollow materials, the teeth expand through the solid part of the block and form an undercut in the cavity. - With vertically perforated bricks, only use rotary drilling (no impact drilling). - Countersunk head screws are recommended for the installation of timber constructions in the case of metal constructions, use anchors with hexagon head screws and moulded washers.