What It Does:
Uses relatively new magnetic technology to bond positively charged proteins to negatively charged, damaged, porous areas on the hair strand—creating a smoother, silkier surface that makes hair easier to style and brush. The fortified strands are less prone to breakage. "The damaged areas do absorb conditioners," Cannell says. "But after a week or two of regular use, you reach the maximum level of repair."

What It Doesn't Do:
Repair split ends or speed up the growth of broken strands.

What to Look For:
Formulas rich in proteins (such as silk or wheat) and vitamins (especially B and E), which repair rough spots in the strands' surface. Also important are moisturizers that contain fatty alcohols (cetyl, stearyl or ceramides) and oleic acid.