Take-Home Bulk Kit: (40) 1.2 ml syringes, 10 refill boxes of 4 16% Carbamide Peroxide Syringe Daytime use: Wear 4-6 hours, once per day. Nighttime use: Wear 8-10 hours, once per day. 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.