The BBQ Buddy features a dual-ventilation system, with one vent on the Lid and one vent at the base of the Fire Bowl. You can manually adjust these vents to maximize or minimize oxygen flow and therefore adjust the intensity of the heat from the charcoal. To increase temperature for searing, rotate the air vents wide open. To decrease temperature for slow cooking, partially close the vents. 
WARNING: The vents and the metal surfaces around them will become very hot during grill use. Use grill mitts or hot pads to adjust vents when the grill is in use.