Super Knife Sharpening System7" overall. Black composition construction. Features a fine ceramic wheel and a hardened alloy metal coarse sharpening wheel. Also has an interchangeable 600 grit (fine) diamond sharpener in bottom of base and a 400 grit (medium) serrated blade sharpener that tucks away inside base on side. Easy and convenient to use. Use on knives with single or double faced blade edges. Easy to hang on the wall or workbench. Sharpens dull knives in minutes! Defeat a