Take-Home Bulk Kit: (40) 1.2 ml syringes, 10 refill boxes of 4 35% Carbamide Peroxide Syringe Daytime use: Wear 20 minutes, once or twice per day. Allow a minimum of one hour between wear time. Do not exceed 20 minutes per application. PRO-SYS® Professional take-home whitening delivers a high-performance system for a more radiant smile. Available in your choice of carbamide or hydrogen peroxide formulas, PRO-SYS® supports a wide range of uses. To eliminate sensitivity, PRO-SYS® contains potassium nitrate and its water-based gel keeps teeth hydrated.