Breather bags are small, portable oxygen containers that allow users to breathe in concentrated oxygen. They are often used by individuals with respiratory issues, such as asthma or chronic obstructive pulmonary disease (COPD), to help alleviate symptoms. The bags typically have a capacity of 100% oxygen and are designed to be lightweight and easy to carry. However, it's important to note that breather bags should only be used under the guidance of a healthcare professional to ensure safe and effective use.