Boar brush spreads natural skin oils over the whole length of a hair. Because hair come in closer contact with the bristles it gives also extra shine and it helps with dry hair. It is kind of natural moisturizing tool. It straightens (or slicks) very well. These brushes also pick up most dust and dirt from hair. I use it myself when I want my hair straight. Try to buy good quality with soft rubber pad. The best ones made by Mason Pearson but the are very expensive. I have one myself for over 6 years already and I swear by it. I use it sometimes on my furbaby
and he just absolutely enjoys it. The drawback with boar brushes is that it should not be used on wet hair or with any styling treatments or it will desintegrate and bristles will fall off. It will still last a few years but won't last forever like metal pin brushes.