Based on this product's specifications, here are some alternatives and similar models
Inlet Filter for Vacuum Cleaner No name KAT00068, compatible with Zelmer models 1500.0032/400/323
Summary description:
Inlet (intake) replacement filter designed for vacuum cleaners, model KAT00068 compatible with Zelmer reference numbers 1500.0032/400/323. Serves as a primary dust and particle barrier for the vacuum’s air intake, helping protect motor and internal components. Suitable for routine maintenance and filter replacement to maintain suction and prolong appliance life.