Comfortable and breathable: The elastic straps are paired with a perforated polyester cotton fabric to provide a secure, comfortable fit during workouts. The mask fits well for most users. Reduce training time and fatigue: The mask supports lactic acid management to help you train at higher intensity while aiming to shorten warmup and prep time, so you can start your session sooner and push harder. progress with 25 levels: There are 25 adjustment levels to move from beginner to advanced at your own pace, making it suitable for incremental altitudestyle training. Endurance benefits from altitudestyle training: altitude training approaches are associated with improved endurance. This mask enables you to apply that method to everyday workouts to enhance performance over time. Onesizefitsmost and secure fit: The adjustable elastic strap can accommodate a wide range of face shapes and sizes, keeping the mask in place during dynamic movements. Key specifications and attributes: Material – breathable perforated polyester cotton; Strap – elastic and adjustable; Fit – comfortable seal for most users; Adjustment – 25 levels; Use – hypoxia/altitude training to improve endurance and performance. Use scenarios: Indoor cardio sessions: Attach the mask during treadmill runs or stationary bike workouts to simulate altitude training and push through intervals. Outdoor endurance training: Use during outdoor runs or cycling to progressively increase intensity while maintaining control over breathing resistance. HIIT and strength circuits: Incorporate the mask into intensity circuits to challenge breath control and sustain effort through multiple rounds.