Cook multiple racks of ribs on any grill that has a rotisserie spit rod and motor.
There is clearly a lot of clever thought and engineering that went into the Rib-o-lator BBQ rotisserie insert device and the owner of the company is a real sweet guy.
There is a rod that connects to your rotisserie motor, if you have a rotisserie.
Then there are two brackets that go on the rod, each with four arms. The arms hold slotted shelves that hold your food. Turn on your motor and round and round they go like a food Ferris wheel. Well this is the exact same concept used in large commercial restaurant smokers because the heat and smoke enter them from a small area at the back, and the Ferris wheel allows the food to move around in the cooking chamber in and out of hot spots so all of it cooks evenly. The Ribolator isn't going to improve quality of the meat on most cookers, but where it really shines is on the WSM where it can increase capacity.
That said, it can only handle narrow slabs that can be confined within the shelves. Wide spareribs bang into the other shelves and spill the contents out. And if you are only cooking one slab, you have to counterbalance the opposite shelf with rocks or something. Then the meat drips on them.