Hydrofarm Negative ION Air Cleaner 

The Hydrofarm Air Cleaner is the best in its class. It's reliable, efficient and whisper quiet. 

This unique air-hanging unit provides powerful ionization capabilities and has a large filter collector.

It works using a closed electrostatic loop. A negative ion charge is emitted from the end of the emitter while a positive electrical charge is placed on the body of the unit. The charged particles move to the nearest electrical ground which is the disposable collector.

The Hydrofarm Air Cleaner can handle an area up to 20' x 20'. Replacement filters available below.

Carries a one-year warranty.

More info from the Manufacturer (PDF format - Lots of detail.)