Hello Anne, Both brands are clinically tested and scientifically proven to work. SDI polanight containts 1ml gel per syringe and HappySmile contains 3 ml of gel. HappySmile works faster and does not give you any sensitivity. You will have great results from using either brand.

I used happysmiles 35% that worked best for me.

I am a customer and have used both brands but the happysmile brand worked way better and had awsome results. The products both contain dental peroxide it is just different brands. FYI I used happysmile 22% and worked excellent.