Unopened. This product instantly generates and sprays 2.5mg/L ozone water. The ozone in the ozone water quickly decomposes into oxygen and returns to water. No post-treatment such as wiping is required. It can generate highly effective disinfecting ozone water using only purified water/tap water. There is no need to stock chemical solutions such as alcohol or hypochlorous acid. This was a gift, and I am selling it because I don't use it. Thank you.