A needle felting foam block is used as a working surface to protect the needles and your table (or lap!). For needle felting you need something soft for the needles to go into while you are 'stabbing' the wool. You can use a special felting brush or just a household sponge but this foam block is much firmer, will last longer (meaning you can use one block of foam to make numerous pieces), and is better suited to sculptural felting as you can also use it to help with shaping certain pieces, especially flat things such as wings and ears, as well as beaks and noses.