Sturdy plastic with diamond surface and non-slip feet. Ideal for most hand and garden tools. Easy to transport and store. Features 4 different grades: Fine, medium, coarse and extra coarse (600, 400, 300 and 200 grit). Sturdy plastic with diamond surface and non-slip feet. Ideal for most hand and garden tools. Easy to transport and store. Features 4 different grades: Fine, medium, coarse and extra coarse (600, 400, 300 and 200 grit).