PrettyCare Cotton Filter Wick Replacement Part for Mini Portable Personal USB Humidifier(5 Pack) Contains 5 filters Please soak it to be wet completely before inserting to the humidifier and turning it on. we suggest replacing the filter wick every 3 months Product Dimensions: 0.7 cm x 13.5 cm If you have any question ,concern and issue ,please visit our store and contact us by customer service email. Thanks a lot.