Anti-asphyxiation Valve Version Key Features: Single limb non-vented full face mask with an anti-asphyxiation valve for safety in case of ventilator failure RollFit™ seal adapts to different face shapes and minimizes pressure on the bridge of the nose TubeFit™ zones for placement of a nasogastric or orogastric tubes ErgoFit™ with easy clips and breathable fabric to help with fitting and adjusting Available in four mask sizes: extra small, small, medium and large