Bests & Worsts Reviews from Amazon

I've been using this for over a month. I started with the lowest resistance and have upped it once, about ready to up it again. It throws in a whole new dimension when it comes to cardio, and also core training since you're trying to inhale forcefully with the muscles you're already working. I definitely feel noticeably more worn out when I use it, and I find running (which I hate doing) a lot easier now since I've been using it. I bought this in anticipation of a shoulder surgery I'm about to have that will prevent me from running or carrying a weight vest for a long time. I still need something to make me breathe hard while I'm training in slow motion at home. Also, I've always lived at sea level and I feel so useless every time I get some altitude. Thought this would be my only way to fix that. Anyway, it's a great training tool. I am a fairly small female and the smaller size fits me fine. I wear a small gas mask and this is just a bit bigger. I have soft ears but I find that putting the straps over my ears instead of around them works just fine. I rinse it out with hot water afterward, wipe down the inside and hang dry. Dries quickly. Would and have recommended it to people I know who know what training means. **Added bonus, I can now run alone at night and creeper dudes on bikes cross the street to avoid ME! Haha. I win. :D