This setup helped us haul 3 kids through national parks and on weekend camping vacations. Weekender clamshell holds enough that the car/van is not crowded, helping youngsters "stay calm". Rails have two bike holders, there is space for three, if you are interested I have a tandem holder that fits. Clamshell locks, and rack holders lock depending on generation. We used originally on a 1990s Volvo wagon, then a 2003 Dodge Caravan and then (current clamps) on a 2013 Toyota Highlander (current setup will work with any vehicle that has built-in rails on roof).