Pool Blok, 6" x 1.5" x 1.5", Pool & Spa Cleaner, With Telepole Adapter, A Pure Pumice Scouring Stone Cut & Sized For Spot, Surface & Underwater Cleaning Of Recreational Swimming Pools & Spas, Ideal As A Spot Cleaner For Rust Marks, Algae Or Leaf Stains, Pool Blok Quickly Shapes To Any Surface, Concrete, Masonry & Hard Metal Surfaces.