Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great little device!

This is a great little air purifier. I used it to kill the neighbor's cigarette smoke that seeps through the walls in my ghetto apartment.I have two. One in my bedroom and one in the living room. Since I don't have central air, I place these under my window unit air conditioners to shoot the cold air up, where my ceiling fan circulates it around the room. It's kept it much colder, and much cleaner smelling in the rooms than last summer when I didn't have them.You can also scent a small piece of paper with your favorite cologne or perfume and place it behind the filter to fragrance your room!