For use with metered dose inhalers. Makes using your MDI easier. Helps eliminate unpleasant taste of medications. One-way valve can be replaced to increase OptiChamber's lifespan. Easy to clean. Made of durable impact-resistant polycarbonate. Face masks (available in small, medium and large) can be easily attached or removed from OptiChamber as needed to assist in medication delivery. Whistle helps you inhale at the right speed.