Strong Ozone Generator 4000 Sq Ft: This ozone generator has max ozone output of 77000 mg, and the ozone machine odor removal can cover up to 4000 square feet of space. And it has a built-in the latest upgraded ceramic ozone board, which is sturdy and durable and has a long use life, easy to clean. Easy To Use: Adopt a horizontal output design. The timer knob can be set for up to 180 minutes, and the "HOLD" setting can also be used continuously use. We suggest that to set a timer before you leave the room, ensure that no people (or petsplants) is in the room when it is working. It can start from 10 minutes and increase the setup time if necessary, depending on the size of the space.