Salter Labs Percent-O2-Lock® Air Entrainment System Transparent, with Humidity Cup, 7Ft Oxygen Supply Tube and Mask, Elastic HeadstrapA transparent, air-entrainment, elongated mask with soft anatomical under the chin shape. A rotating sleeve air entrainment valve allows you to dial in seven different oxygen concentrations: 24, 26, 28, 31, 35, 40 or 50%. Aluminum nose clip aids in a positive fit for appropriate oxygen % delivery. Over-the-ear or elastic head strap styles. Standard with three channels, crush resistant safety tubing. A high humidity adapter permits use of a nebulizer with this assembly. Single unit variable Venturi System delivering accurate concentrations of oxygen (from 24 to 50%) with a single unit.Transparent, air-entrainment mask with soft anatomical shape.Easily adjusted, variable venturi system.Unique, spring-loaded mechanism locks prescribed concentration in place.Wide, adjustable elastic strap or over-the-ear style available in adult configuration.Durable, plastic humidity cup, standard.