Phresh Filters are world renowned as the very best carbon filter canister available. Using only sieved and de-dusted Australian activated carbon, every batch is analysed and tested to ensure it meets 950ID or higher. All carbon particle sizes are 4/12 US mesh or larger, ensuring the highest achievable airflow ratings. Every canister is weighed after manufacture to ensure consistency with every single filter made. Expect a minimum of 2 years life and up to five years life span in low humidity environments.