The kit consists of 7 upper and 7 lower pre-filled trays-enough for 7 days. Easy and convenient entry-level whitening kit provides patients with comfortable pre-filled trays. Each tray features 11.2% Hydrogen peroxide. Features: Trays are soft and flexible Ergonomically designed trays Addition of Potassium Nitrate Benefits: Tray molds and contours easily to the patient's teeth for greater stability. Greater adhesion gently guides the gel between the teeth for whiter results. Trays are virtually undetectable for wearing during the day. Greater comfort for the patient. Reduces the chances of sensitivity.