Oxygen trainer device

An oxygen trainer assembly comprising:

• a mouthpiece having a mouthpiece opening;
• a circulation chamber housing having a circulation chamber in fluid communication with the mouthpiece opening, the circulation chamber housing having a first chamber housing end and a second chamber housing end, the first chamber housing end having a first circulation aperture and the second chamber housing end having a second circulation aperture;
• a first endcap mountable to the first chamber housing end, the first endcap having a first endcap aperture in fluid communication with the first circulation aperture;
• a second endcap mountable to the second chamber housing end, the second endcap having a second endcap opening in fluid communication with the second circulation aperture;
• a first endcap insert disposable in the first endcap, the first endcap insert having a first endcap insert opening, the first endcap insert opening being aligned between and in fluid communication with the first endcap aperture and the first circulation aperture, the first endcap insert opening sized and configured to control the level of air resistance into the circulation chamber during inhalation and out of the circulation chamber during exhalation;
• and
• a one-way valve disposable in the second endcap, the one-way valve being sized and configured to allow the flow of air from the second circulation aperture and away from the circulation chamber during exhalation and to block the flow of air from the second circulation aperture and into the circulation chamber during inhalation.