QISE Training Mask 4.0 with 8 Filters Workout Mask 48 Levels Breathing Resistance Levels - Fitness Mask Training in High Altitude Simulation Increase Cardio Endurance

This training mask cannot increase haemoglobin levels, it will never be like altitude training. There are no studies that show otherwise. However, it is pretty good for training your lungs in general. Your lungs get stronger, bigger, and your body learns to do more with less - efficiency. It's also a good way to practice new breathing techniques. For example if you're a long distance runner, learning to breathe through your nose and out your mouth is pretty convenient.One problem I had with this product is that if you have it on the "Advanced" setting or higher and have the mask on for a long time, the bridge of your nose will start to ache.I bought this mask not for the altitude training part, just the resistance training.

Not a universal size, as described;LARGE is what I recieved... waaaaay too big for a woman. Material is not what was expected; seems as if it may easily tear, No filters, No Case, Will Return!!!! Extremely disappointed. Not worth the $$$ at ALLLLLLL if the material easily rips.My other training mask is spectacular, thought this one would be the same, guess not.

Product is as described by seller.

The worst ever.The product arrived late and the quality is terrible.I would not recommend it.