This high quality nylon rotary floor machine brush is great for more aggressive carpet and rug washing. Nylon is flexible and supple enough to gently scrub wool rugs, yet it is more resilient than other fibers, giving better results with a longer brush life. The outer rows are black nylon with a 0.030 fiber fill and softer white nylon 0.025 fiber fill for the inner rows. Don’t be fooled into buying low performance polypropylene brushes. Better quality brushes perform better and pay off in the long run too.