They have a modified working knuckle. The knuckle is held in a closed position by a spring pressure or gravity. An uncoupling is accomplished by stopping them over a magnetic field. These couplers are both more effective and realistic looking. Lightly lubricate each coupler pocket with graphite.
Good coupling depends on proper positioning.
If a coupler is too high you can place a shim between the coupler pocket and the car floor. If it's too low, you can either cut away the under frame or add washers between the truck bolster and the car body. You also must make sure the trip pin height is correct. If the trip pin hangs too low it will sag in your track work, and if its too high it won't uncouple. Converting your pike from one type of coupler to another is very difficult.