[0] Bleach [1] Tooth whitening gel that is professional strength with 10%, 15%, & 20% carbamide peroxide that maximizes teeth whitening. [2] Tooth whitening gel, professional strength with 10%, 15%, & 20% carbamide peroxide to maximize teeth whitening (Same procedures & products used by dentist.). [3] 
Not professional strength carbamide peroxide that does not maximizes teeth whitening. Takes more gel to get teeth whitened because of its lack of strength.