ARRIS SURFboard SB6121 4x4 DOCSIS 3.0 Cable Modem (Certified Refurbished)-Black This Certified Refurbished product is manufacturer refurbished, shows limited or no wear, and includes all original accessories plus a 90-day warranty. IMPORTANT NOTEL: A few units might show the brand as Motorola (and not Arris) as Arris had acquired Motorola for 2 years; hence it will be the same product and the same model Requires CABLE Internet Service, if not sure your provider is CABLE call them to confirm. Does NOT work with Charter cable provider. Compatible with MOST Major CABLE providers like Comcast/Xfinity, Cox, Time Warner, Mediacom, Bright House. Wired modem only, does NOT include WIFI Router or VOIP Telephone adapter. Gigabit Ethernet port to connect to computer or Router for fast downloads. Internet download speeds up to 172 Mbps and upload speeds up to 131 Mbps based on your Cable provider service. Good for streaming Video and gaming on multiple devices at a time.