TRINITY GLASS CAP: Nightmare and Valhalla 28 For Nightmare RDA 28mm and Valhalla RDA 28mm THIS CAP REFLECTS NOT ONLY HIGH QUALITY AND AESTHETIC, BUT FUNCTIONALITY FOR THE CLOUD CHASER. OFFERS THE SAME PROPERTIES THAN THE REGULAR GLASS CAPS BUT WITH AN EVEN MORE GENEROUS AIRFLOW AND MUCH EASIER DRAW FOR THE ULTIMATE CLOUD EXPERIENCE. MAINTAINING VERY GOOD FLAVOR ALL THE TIME. FEATURING A 10-12mm BORE ON TOP AND TWO 8-10mm WIDE AIRFLOW SLOTS. SIZES BASED ON ORIGINALS ATTYS. SIZES ARE DIFFERENT FROM EACH OTHER.