3-Channel Vented Chest seal 
10pcs a box
This innovative device provides 3-vented channels that are designed to prevent airflow into the chest cavity during inhalation while allowing air to escape through the vent channels during exhalation. The 3-vent channels are designed to allow blood to escape and also provide a backup fail-safe system, as even if two of the three channels become obstructed, the vent is designed to remain fully operational.