Overlay battens are needed, if using any of the flipchart easel overlays in conjunction with a Learning with Linden overlay holder. Battens may also be fitted simply to assist holding the overlay in place or helping to keep it flat while in use. Made from yellow foamex plastic. Sized : 600 x 30x 4mm. They attach to the overlays using double sided tape and plastic 'press together' rivots, which are supplied with the battens. One pair of battens is required per overlay. (Set of 20 also available)