Our Boost Hair Serum contains polygonum multiflorum extract, ginseng extract and Batana oil; Roller make of Stainless Steel. It nourishes and protects hair, as well as improving the health of hair follicles, promoting hair growth, retaining hair moisture, and replenishing hair's natural oils to protect hair. The way to use it is very simple: apply an appropriate amount of essence to the scalp, gently roll the roller, taking care to maintain the moderate strength until the product is fully absorbed. It can help repair damaged hair, deeply awaken dormant hair follicles, promote the growth of new hair, and make hair healthier and thicker.