A nail is to a dab rig what a bowl is to a bong. If that makes no sense, think of it this way: Dabbing is the method of consuming cannabis concentrates by way of high heat and inhalation. In order to heat concentrates enough to vaporize them, you need to put them somewhere. That's where the nail comes in. Whether you go with titanium, ceramic, or quartz, your nail should be well-built and able to withstand high temperatures.