A carb cap is an essential instrument designed for use with domeless nails. To use a carb cap, heat up your heating element, put your oil or concentrates on the nail, and then place the carb cap over the domeless nail.
These devices have a small hole to restrict airflow to your nail and increase flavor. If you dab without a carb cap, you’ll be constantly pulling cold air into the chamber of your nail. This flow of air will cool down your heating element and concentrates before you are able to enjoy all of the flavors your concentrates have to offer.
Dabbing without a carb cap forces you to take higher temp dabs, destroying the terpenes in your concentrates. Terpenes are responsible for the flavors of your concentrates, and also alter your smoking experience—why would you want to waste that!?