Open box condition, used once, like new. Original unit was $300. Will deliver on-campus and nearby Stanford area as well! Great for filtering smoke, odors, dust, mold, pollen, and other allergens. Quiet; not louder than a whisper on low (~31 dB) and at most the noise level of rainfall on high (~56 dB). For mid-size rooms up to 540 sqft. Measures 13" x 13" x 21". Each filter up to 4,380 hours of use.