The Vornado AQS500 is unlike most air purifiers. It's signature Vortex Technology provides Whole Room Air Circulation and optimal cleaning. The air passes through two Vornado Allergen Reducing Filters. It captures serious allergens like dust, pollen, pet dander, smoke, bacteria, mold spores and dust mite debris. Vornado is backed by a five year limited warranty for it's dependable craftmanship. You can place t against the wall or in any corner. It's as quiet as a desktop PC with a  near silent operation. The Vornado AQS500 has additional features like a timer, speed settings, change filter indicator...