The one-way valve included in Primacare KC-1010 universal mouth-to-mask CPR kit eliminates blowback to make sure that you are protected from communicable ailments and disease. It also provides you a soft-air cushion for leak-free performance. The first responders kit features an adult-size CPR mask, a child-size CPR mask, a pair of gloves, and a carrying case. The masks provide a proper seal and have an O2 inlet for attaching supplemental oxygen.