High Altitude Mask, Training Workout Mask Men to Improve Lung Capacity, 24 Level Breathing Resistance Fitness Mask to Upgrade Endurance, for All Sport: Running, Cardio, Cycling, Gym, HIIT

Good

I am absolutely amazed this thing is comfortable, and I think it has helped in my goal of doing altitude training. I'm still using the lowest setting with brief excursions into a middle setting. My oxygen saturation will go from around 98% to about 96% with mild activity which is significant for a device that is not directly changing O2 percentages

Exactly what i was after.

This really makes a huge difference in your stamina I'll put this on and just go for a 30 minute walk and you'll notice the difference in your endurance real quick...

This mask is great for boosting your training intensity. It made me feel like I couldn’t breathe after only one minute of running in it, so it definitely does the job! The only issue with it I had was the mask kept sliding down my nose and I had to keep pushing it up during my run.