I have purchased several of those mesh nebulizers through amazon, and loved the quiet and speed with which they work. I found none lasted more than three or four months used once a day, despite following the cleaning instructions with distilled water and/or vinegar. Now that I'm nebulizing twice a day the last one lasted less than two months. I did replace it, but am saving it only for use away from home. The medicine cups with the mesh are only warrantied for 3 months, so I guess that is the life expectancy.