Feature: 1. Effectively filter PM2.5 fine particles, make sure you get air when using the respirator. 2. Filter cotton is equivalent to a protective barrier, can prevent particles in the air from entering the respiratory tract through tube and . 3. Adopts quality material, high density filter cotton, mild and non-irritating, good filtering effect. 4. An important accessory for respirator, effectively extend the service life of the machine. 5. Light weight and in small size, easy to carry and install on machine. Specification: Condition: 100% Brand New Item Type: Filter Cotton Fit For: For ResMed S9/S10 Size: Approx. 5.3 x 3.5cm / 2.1 x 1.4in Operation: 1.Open the machine and take out the used filter. 2.Put a new filter at the air intake and close it. Make sure that the air filter is fitted tightly to prevent water and dust from entering. Package List: 1 x Bag of Filter Cotton(20pcs)