I get this Motorola SB6121 Modem to replace a old sb5100 Cable modem . while the seller I purchase from turn out to be a total scam , Amazon make good with a full refund . this modem really be fast !! I have cox Cable Preferred service which guarantee 15mbp download , and I get consistant 20 + mbp on any test site I use . Works great . if you need a cable modem , this be the one to get .