Based on this product's specifications, here are some alternatives and similar models
Expansion vessel Reflex N for central heating, model N 300 L (8215300), 300 litres
Summary description:
Reflex N expansion vessel for central heating systems, model N 300 L (8215300) with 300 litres nominal volume. Designed to accommodate thermal expansion and maintain system pressure in closed C.O. installations. Features a diaphragm separating air and water, connection fittings for integration into heating circuits, and corrosion-resistant construction for reliable long-term operation in residential or commercial heating applications.