Works perfectly with Comcast up to 300mbps. Is on their approved 3rd party list. Don't pay the monthly fee to rent their modem, get this one time and save money. Sticker on bottom on modem has MAC address number Comcast needs to set it up and you're good to go. Comes with Ethernet cable (not pictured). New costs 100. Renting a modem from Comcast costs you every month. --- Product Description Building upon the success of the SB6121, Motorola's SURFboard SB6141 enhances your personal media experience, at lightning-fast broadband speed. It harnesses the power of DOCSIS 3.0 technology to bond up to eight downstream channels and four upstream channels--providing you advanced multimedia services with data rates up to 343 Mbps download and 131 Mbps upload depending on your Cable Internet provider service. That makes streaming HD Video, gaming, shopping, downloading, working, high-quality voice and video conferencing, and peer-to-peer networking applications far more realistic, faster, and efficient than ever before.