This Certified Refurbished product is tested and certified to look and work like new. The refurbishing process includes functionality testing, basic cleaning, inspection, and repackaging. The product ships with all relevant accessories, a minimum 90-day warranty, and may arrive in a generic box. Only select sellers who maintain a high performance bar may offer Certified Refurbished products on Amazon.com Convenient leave-in wireless receiver: Tiny nano receiver stays in your computer so your headset is always ready to use Clear stereo sound: Laser-tuned speaker drivers and noise-cancelling microphone for clear calls. Frequency response (Headset): 40Hz - 10KHz , Frequency response (Microphone): 100Hz - 6.5kHz