Large Round Brush The inside of the Large Round Brush 43 mm is of magnesium. The heat is retained and conducted better, which shortens the drying time. The brush has an anti-bacterial coating and is made of two high-quality materials that together form the best of both worlds: nylon bristles and cruelty-free wild boar bristles. The soft nylon bristles detangle the hair without damaging it. The boar bristles ensure that the hair does not become static, gives a lot of shine and makes the hair soft.