3 car trailers are trailers that can carry 3 cars with one tow vehicle.  Generally speaking these trailers come in 2 varieties, open gooseneck or gooseneck stacker trailers.  The 3 car stack trailer will include a lift and two cars will be raised on to the upper deck, while one car is kept on a lower level.  3 car trailers also include a tie down system that will have a minimum of 8 tie down points, put often more.  E-Track is a good idea if the cars you will be hauling are different sizes.  A 3 car stacker trailers normally are a minimum 44 feet and come as long as 53 feet.  3 car open trailers are a minimum of 48 feet and as long as 53 feet.   A stacker trailer is generally recommended due to the protection they provide from road hazards during transport.  These stacker trailers can contain living quarters are utilize lift gets to raise cars to the second level.