Compact and lightweight so that you can take it with you while on the go Safe and Comfortable: Our spacer is made of durable plastic and soft soft silicone Visual Airflow Indicator; letting you know the correct speed breathe Tight air Seal around nose and mouth insuring no waste The NESSI is a spacer intended for use in the inhalation of medications which are provided by OTC MDIs. The device consists of a translucent housing a back piece and mouth piece or face mask.