Based on this product's specifications, here are some alternatives and similar models
Heat recovery unit dummy (cover) SpiroFlex E-RVC3HEB-OB for rekuperators, model E-RVC3HEB-OB
Summary description:
SpiroFlex E-RVC3HEB-OB is a dummy/cover designed for heat recovery ventilation units (rekuperators). The product functions as a non-operational placeholder or protective cap for the specified model E-RVC3HEB-OB, providing protection for duct openings and components during installation, maintenance, or storage. It is intended for use with compatible SpiroFlex ventilation systems and helps keep ducts sealed from dust and debris.