Laser hair growth caps are head-worn devices that use laser diodes to stimulate your scalp and promote hair growth. 

Although the specific design of these devices can vary, most look like a baseball cap with laser diodes on the inside. Many laser hair growth caps feature hundreds of laser diodes designed to target your scalp from every possible angle.

The idea behind laser hair growth caps is simple. Research suggests that exposure to low-level laser light stimulates cellular activity. By exposing your hair follicles to concentrated laser light, a cap may be able to promote hair growth and improve your hair in areas with hair loss. 

Other laser hair growth devices, such as combs, bands, helmets and others, are all designed to take advantage of the same theory. 

Like many other hair growth devices, laser hair growth caps can vary hugely in design, cost and quality. 

Simple devices that feature a few hundred laser diodes with a low to moderate output are often available for several hundred dollars, while high-end, high-powered devices with thousands of laser diodes are often priced in the “thousands of dollars” range.