Lot of (4) BulbHead Air Police Compact Wall Outlet Air Purifier Ionic Technology w/Built-in On/Off Switch Nightlight. (2) are new in box & 2 are barely used w/o box. By selling a lot of (4) you can add one to about every room! The stainless steel filter never has to be replaced. Air purifiers neutralizes odors while helping reduce pet dander, dust mite matter allergens and smoke from the air.