Three tungsten carbide teeth for use on the Arbortech industrial woodcarver blade. The cutting teeth are rotatable and replaceable so there's no need for sharpening. With a life of almost 25 times longer than the Pro 4 blade it may be some time before they are required replacement. From a purely economic standpoint the Industrial Arbortech is a sound investment. Its extreme long life, replaceable teeth and ability to cut a wide variety of materials make it excellent value for money.