THE OFFICIAL BAS RUTTEN RESPIRATORY TRAINING DEVICE - Designed by Bas Rutten himself to increase inspiratory (inhalation) muscle endurance, the O2 Trainer is a lightweight breathing device that regulates air intake and improves muscle oxygen efficiency during exercise. RESULTS AFTER ONLY 30 DAILY REPS - The O2 trainer is more than just a tool for athletes to improve their training. In just under four minutes of work, 30 reps with the O2 will strengthen your lungs and breathing muscles in your upper abs. Training your breathing in this way benefits your everyday life! STRENGTHENS YOUR INHALE MUSCLES. The o2trainer Strengthens your Muscles responsible for opening up your lungs (your diaphragm and external intercostal muscles). You will be able to move up to 5 times more air in and out of your lungs and faster. PORTABLE KIT DESIGN – Both the trainer and the inserts have been designed to fit in an easy to pack portable kit. The O2 kit fits in any gym bag