The Levoit Core 400S is a HEPA air purifier made by Levoit. The Core 400S features an integrated PM2.5 air quality sensor and WiFi. The Levoit 400S can be managed remotely using the VeSync mobile app.
The Levoit 400S is a cylindrical shape, with a cylindrical HEPA filter inside. The internal filter has a pre-filter layer on the outside, the HEPA filter, and an activated carbon 3rd filter layer. The layers are not replaced independently -- when the filter is no longer working properly, a new filter is needed.
The Levoit 400S has an auto mode as well as programmable modes (via the VeSync mobile app) that allow it to automatically respond to changes in PM2.5 levels.
The Levoit Core 400S produces a CADR of 260 CFM ("clean air delivery rate"), is between 24 and 52dB loud depending on which mode the unit is operating in, and is rated for 38W of power.
COVID-19 usage tips
If using the Levoit 400S to mitigate indoor air COVID-19 risk, the unit should be run on HIGH if the noise level can be tolerated. If HIGH is too loud, then the second-highest setting should be used. While the Levoit 400S has an "Auto" mode, this auto mode is designed for responding to high levels of particles in the air from things like pollution, cooking, etc and not COVID-19.
On the highest speed setting, the Levoit 400S produces a CADR ("clean air delivery rate") of 260 cubic feet per minute. This means that to achieve at least 6 air changes per hour (the "good" target recommended for COVID air mitigation), the Levoit 400S should be used in a room of no more than 290 square feet (assuming 9 feet ceilings). If used in a larger room, multiple units can be used or outside air ventilation can be added. See the air cleaner purification calculator from Harvard and CU Boulder for more information. The air cleaner will also work in larger rooms and will likely reduce risk, but the 6 air changes/hour target may not be met.