Google around and look at the reviews and forum threads (Long Hair Care, NaturallyCurly) for Garnier's Blow-Dry Perfector. There are very few individuals reviewing that product who got the desired results and many who were very unhappy with it (not that reviews are always trustworthy - but there's such a strong consensus out there that this product isn't worth your time that I decided not to mess with it).
I asked a similar question in "Ask the Beauty Brains" about safety of Organix BKT 30-Day Smoothing Treatment. I had a great experience with this grocery-store product, but I've been getting concerned about potential dangers of the active ingredient - oxoacetamide - of which I can find out almost nothing!
All of the temporary straightening products rely on heat to straighten the hair--more heat than you would normally need if you were blowdrying chemically straightened hair. As a consequence, you risk doing more damage to your hair if you regularly use them than you would with a properly applied chemical straightener.
For a year, I used keratin treatments to straighten my 3B/C hair and in addition to permanently straightening sections of my hair over time, my hair wound up more fragile and damaged than it ever was when I got chemical relaxers. If your hair is really curly (e.g.,Alicia Keyes natural hair), my advice to you is to use these treatments only if you want to wear your hair straight for "special occasions", but if you're looking to regularly wear your hair straight, consider having a trained professional relax your hair.
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