Spline lug nuts,the diameter is only 20mm,available for wheels with small diameter recesses. A no-compromise design engineered to fit small diameter recesses in new tuner wheels. Spline lug nuts offer a closed-end design, maximum gripping power, more stud engagement and a greater seating surface than socket style lug nuts. In addition they’re 30% lighter in weight. Spline lug nuts take safety, dependability and good looks to the next level.It can replace the common nut.Another advantage is spline nut key with grade 10.9. The material is CRV. The key passed over 72 hours heat treatment and hydrogen treatment. Not only the hardness could reach to HRC38-42,but also could ensure the ductility and prevent crack.