The ACS is a safer approach to treating open pneumothorax and preventing tension pneumothorax in chest injuries from gunshot, stab wounds or other penetrating chest trauma. The unique one-way valve is designed to let air and blood escape while preventing re-entry of either. Proven to be a more effective treatment than standard petroleum gauze, the ACS is standard issue for the U.S. Army and the U.S. Navy. Product Specifications: Clear circular design. One-way valve. Gauze pad included. Strong adhesive. Sterile. Easy open package. Product Benefits: One-way valve to let air and blood escape while preventing re-entry of either. Ample dressing size of 5.5 inch diameter. Gauze pad for cleaning and drying wound area. Clear pad design for optimal visualization of wound. Pressure-sensitive adhesive assuring effective seal, even through body hair.