Carb Cap A cannabis carb cap is a device used to control the flow of air and vapor when dabbing cannabis concentrates. It works by covering the nail on a dab rig and partially covering the bowl, allowing the user to trap the vapor and create a lower temperature environment. This results in a smoother and more flavorful dab. Cannabis carb caps are typically made of glass, quartz, titanium, or ceramic materials and come in a variety of shapes and sizes. Smaller carb caps tend to be more efficient at trapping the vapor, while larger ones provide more space for vapor to circulate. The different materials provide different levels of heat retention, depending on how much insulation is desired. The main purpose of a cannabis carb cap is to allow the user to lower the temperature at which they are consuming their concentrates. By controlling the air flow, they are able to lower the temperature enough to create a smoother and more flavorful dab. This is because lower temperatures allow the terpenes, which are the molecules responsible for the flavor and aroma of cannabis, to vaporize more easily.