NETGEAR Certified Refurbished CMD31T-100NAR (4x4) Cable Modem - for Comcast, Cox, Cablevision NETGEAR Certified Refurbished products have been inspected, reconditioned, and tested to work and look as good as new with all accessories and documentation. You can buy with confidence knowing your Certified Refurbished product is backed with a 90-day warranty and support. Not Compatible with, Spectrum, Time Warner, Brighthouse, or Charter High-performance - Up to 150 Mbps download and upload speed for streaming HD videos, faster downloads, and high-speed online gaming For NETGEAR refurbished products the serial number is removed from the label. If your Cable Internet Provider requires the serial number during installation it can be retrieved using the included flyer