Audio-Technica ATH-ANC23 QuietPoint Active Noise-Cancelling In-Ear Headphones (Certified Refurbished) This Certified Refurbished product is factory refurbished, shows limited or no wear, and includes all original accessories plus a 90-day warranty Reduce distracting background noise by up to 90% while offering superior sound Engineered to create a comfortable listening environment in areas with high ambient noise Feature a miniature microphone in each earpiece that picks up ambient noise Electronics in control box create a noise-cancelling wave that is 180 out of phase with ambient noise-wave acts as noise eraser