The 3620-14WD & 4220-14WD, models share the same robust design and features, differentiated with either a 36″ or 42″ serrated blades. These heavy-weight disc harrows are ideal for contractors who primarily use 4WD tractors from 300 HP and larger. No matter what the task: land clearing, road building, fire breaks, or soil blending, these disc harrows are built to take on any condition. The 36″/ 42″ notched blade are spaced 20″ apart for deep plowing in heavy trash conditions, mixing and aerating varying soils. Large heavy-duty ductile cast spools have thicker sidewalls than fabricated spools, providing superior durability against rocks.