Skimlite Spartan Series 22" All-Purpose Nylon BrushThe Skimlite Spartan Series 22" All Purpose Nylon Brush uses a stronger, thicker and harder bristle that standard nylon brushes. This uses a PBT (Polybutylene) bristle material instead of the PP (Polypropylene) bristle more commonly used in the pool industry, which produces a better and more efficient clean due the stronger nylon bristles. The PBT material does not deteriorate as quickly and will not become brittle like the PP bristles will. This