A groove in the ground facing side of the horseshoe in which the nail holes are stamped. At the level of the surface, the groove has a width of approx. 6 mm: equivalent to the width of the nail being used, at the bottom, the groove runs to a point - the sides of the groove are not necessarily symmetrical in slope. The fullering may run the whole length of the shoe or be restricted to the quarters. Fullering increases traction compared to a conventional stamped shoe. The process of applying this groove is also known as fullering.