The Omron 9921 Child Mask Helps Children Comfortably And Efficiently Take Their Nebulizer Treatments. Soft Pvc Material Is Non Irritating To Young Skin. Bottom-Loaded Design With Air Vents Provides Easy Breathing. This ChildrenS Nebulizer Mask Works With Many Omron Aerosol Delivery Systems (Models Listed Below). Lasts For Approximately 3 Months. One (1) Omron Nebulizer Child Mask Per Package.