This is a set of 3 water filter cartridges, each lasting approximately 3 months. It removes 13+2 substances and is compatible with the MONO series. - Quantity: 3 cartridges - Model: MDC01SZ - Usage Period: Approximately 3 months - Number of Substances Removed: 13+2 - Compatible Models: MONO series Thank you for looking. I accidentally purchased these. One bag has been opened, but the cartridges are unused. Please understand that these have been stored at home and the box may have some scratches.