The 12-400 is a plug-to-plug cable and clamps set that provides for convenient, cost effective jump starting.  The battery lead cable is 5-foot long with a plug on one end.  The jumper cable is 25-foot long for easier access to the disabled vehicle.  It is made of 4-gauge welding cable, and features 400 amp clamps on one end, and a non-reversible plug on the other to ensure a safe connection.  This set is appropriate for light to medium duty jump starting.