The new GS4 system - a large, inner cooking bowl surrounded by a hinged grill lid and porcelain coated cast-iron sear plates that fit seamlessly together. This creates an exceptionally large cooking area and gives you the flexibility of grilling smaller quantities of food (under the lid), while still allowing you to smoke larger cuts (by adjusting the air intake vent in the bottom tray). The result is excellent heat control for ultimate barbecuing results.