The Spartan Combo Brush mixes Silicon Carbide (street-sweeper tough!) and PBT bristles for ultimate pool cleaning power. Silicon Carbide bristles won’t rust or poke, are thicker and longer-lasting than stainless steel, and are perfect for rough surfaces like Pebble Tech and Diamond Brite–safe even on new plaster pools. They float if they get loose and tackle black algae without scratching.