The Kyokugen Wheel Lugs are shaped in a heptagonal pattern making each a seven sided lug nut. Kyokugen nuts look like an ordinary lug nut from a distance, but the only way that you can remove them is with the special socket ONLY provided with the set. You'll get added security for your rims. The lugs also weigh 50% less than stock lug nuts (0.9 oz. vs. 2.1 oz.) On a car with 5 lugs per wheel, this can save you more than a pound! These lug nuts are closed ended and 42mm in length.