This is a boar-bristle hair brush built on a real wood base, with a 5-row layout of 100% medium-firm boar bristle. The wood handle carries a UV-resistant coating meant to help it hold up against bathroom humidity, and the bristles are set using Diane's own bristle-implantation method aimed at reducing shedding over repeated daily use. Boar bristle works by distributing the scalp's natural oils down the hair shaft as you brush, which is what gives hair a smoother, glossier look and helps tame frizz and flyaways over time. Medium firmness is a middle ground: stiff enough to work through thicker or coarser hair, but gentler on the scalp than a hard-bristle brush.