Teeth whitening strips

I'm sure this has been posted about a zillion times but I can't find it. Anybody used the crest strips? Would you recommend? If so which type and where did you buy them?

Yes, I loved them. Used them for my wedding and other events. My sister suffered some teeth sensitivity, but I didn't. It's been a while, but I bought mine on www.valueventure.ie Can't remember what they cost, sorry.

I got them while I was in America a few years back and didn't find them all that great tbh... plus they made my teeth very sensitive bordering on actually sore for a while afterwards!