I've been using a SmartVest for 8 1/2 months. Day to day progress seems slow but I can now take deep full breaths and it's wonderful. I do have days when I am congested but never fail to use my vest 2x/day. I use a nebulizer at the same time, postural changes 10 minutes 2x/day and my aeribika 2x/day. I really believe the vest and the rest of my routine are helping me to get stronger and breathe more easily. I'm 75 years old and intend to keep doing this until a miracle drug is invented.