I use my Pari Trek S as my daily nebulizer. I keep it plugged into the wall for daily use and take the battery pack with me on trips. As far as strength, it seems to meet my needs. I will say that if you are using it on battery, you do have to recharge the battery after only a few treatments. But all in all, I am happy with this unit. It's not quite as loud as my old Phillips and the Pari cups last six months, which I appreciate.