when you have xbox 360, dvd changer, ps3, indash monitor w/ dvd, and front and rear cameras. and your vehicle os equiped with 8 tvs you would use the selector to have lets say the headrest playing one thing, your indash playing another, and your visors playing another just for example. I saw them b4 but now i cant find them.
The 4 to 1 is only good when you have 1 output source or your just playing 1 thing on all your monitors
let me know if you know the name and or place where i can find them