Flagged bristles, also known as feathered bristles, have split ends that create a frayed sweeping surface. Brooms with flagged bristles work best on dry surfaces to sweep up fine dirt and dust.Unflagged bristles are not split, which helps keep the bristles from clogging and matting together. These types of brooms are great for rough or wet surfaces with heavier debris, such as garages and kitchens.