I have had a 3.0 for over a year now and it has greatly enhanced my lung capacity as well as my familiarity with the uncomfortableness of being out of breath. I am working and playing in Nepal at higher elevations for much of each year and I use the 3.0 over there prior to moving to the higher elevations and it makes a noticeable difference. The only issues will more than likely be with yourself. Be warned that when used properly, the Training Mask will take you out of your comfort level and push you a bit.

I received my set 3 weeks ago and the mask is working perfectly. No issues with the mask. However the wireless ear bud headphones only the right one works. After charging the headphones and pairing them at least 3 times the left one will not work at all. Anyway I am happy with the product overall, I just wish my headphones worked.