I've heard most tooth related products by crest are amazing, but I think it's only the ones coming from the US? I looked at the ingrediants and they say the supreme whitening strips contain 14% Hydrogen peroxide, I went through a stage of just buying bottles of HP online and just dabbing a tiny bit on my toothbrush (big bottles are like... £5) Only thing is that both contain acid so it can erode stuff after a long time. (just my 2 cents!) I looked at the whitening strips and YOWZA expensive