Karisma In-Office Regular Strength Double Session is a 2 Pre-Filled Tray for back to back 20 Minute Sessions. Allows quick delivery, No Preparation Time, Minimal Chair Time. Includes Potassium Nitrate to eliminate Tooth Sensitivity. Includes: 2 Pre-Filled Dual Arch Trays 2 Vitamin E Oil Applicators 1 At Home Re-Fill Syringe (3.5 ml)