Water Filled A-Frame Display Board. A sturdy A1 Outdoor Sign Holder moulded from polyethylene, with a hollow core that can hold up to 35 litres of water (if required), these display boards are both durable and extremely stable in all weather conditions. The signs can be up to 5mm thick and simply slide into aluminium channels on the edge of each side. The display are then hinged at the top for easy portability and storage. Available in grey as standard but custom colours can be manufactured, subject to minimum order quantities apply.