This product is designed to prevent dust and dirt from accumulating on ventilation fans in toilets, changing rooms, and bathrooms. ● It's an adhesive filter, so it's easy to install like a sticker. ● You can cut it to fit the size of your ventilation fan. ● It uses non-woven fabric with anti-mold and antibacterial treatment. Product size: Approximately 30x30cm (can be cut with scissors to fit 20cm or 15cm ventilation fans) Contents: 20 sheets