This GEAR Premium directional airflow carb cap is designed to be used with thermal bangers. This carb cap is made from high-quality borosilicate glass and built to control airflow and seal off heat from escaping. This GEAR Premium directional airflow carb cap is designed to be used with thermal bangers. This carb cap is made from high-quality borosilicate glass and built to control airflow and seal off heat from escaping.