Long lasting PARI air filters last up to 500 hours. Filters also fit the PARI Proneb Ultra, although you will need the filter remover tool which is not sold with this set. Filters should be replaced at least every 500 hours or when they appear dirty. Check air filter every 6 months (when you change your PARI reusable nebulizer set) to be sure it does not appear dirty. Each pack comes with 3 filters.
These filters are not meant for the PARI Vios Pro nebulizer compressor.