Question: what are the strongest whitening strips?
Answer: Product description Crest Whitestrips Supreme has 100mg of gel with 14% hydrogen peroxide = 14mg of hydrogen peroxide per upper strip. Crest Whitestrips Professional has 200mg of gel with 6.5% hydrogen peroxide per upper strip. Crest Whitestrips Supreme is the most effective of the Crest Whitening Strips.