This is an IST PROLINE O20 Octopus. This great Octopus features: O20 Octopus Regulator Quality construction Superb precision engineering Rugged, dependable and affordable Designed for reliable functionality Lightweight, ideal for reduced jaw fatigue Soft black silicone mouthpiece Exhalation is controlled by an oval exhaust diaphragm which opens with radius bends to create a tighter seal Super quality, comfort, and cost.