Natural bristle is stiffer than horse hair and goat hair, but being a natural material remains gentle and forgiving on the skin. Its excellent brushing characteristics make this brush good for muddy conditions as well as for general grooming, and it is truly a great all rounder. If your horse is sensitive, you might try the 1595, where the bristle is longer (and feels softer). If you want colored bristle, see the 1654.