Many smoothing serums are aimed at coarse or frizzy hair, though many formulations are also labeled for all hair types and for textured hair.
Smoothing products are typically sold as serums or hair oils. Bottle sizes in the results range from about 1.6 fl oz up to 6 fl oz.
They typically promote frizz control and smoothing while enhancing shine, adding moisture or strength, and some also advertise heat protection.
Some smoothing serums state they provide heat protection. At least one formula in the results specifies protection up to 450°F; however, not all products list a numeric heat-rating.
Reviewers commonly report that smoothing serums feel non-greasy and non-sticky, absorb quickly, and that a small amount is effective.