THE CLAIM Most smoothers keep hair fuzz-free for a few blissful hours. But this two-step, heat-activated treatment (containing rice oil and the amino acid cysteine) promises sleek hair for three weeks. THE EXPERT SAYS "It's a mild relaxer," says hair stylist Rona O'Connor, who works with Blake Lively. "It will make your hair smoother, but you're dealing with chemicals, so follow directions closely or it can fade your color or dry your ends." OUR VERDICT Our frizz-prone hair air-dried without expanding for 10 days.