This listing contains 89a Durometer Inline Wheels. These wheels are perfect for outdoor skating, and utilize the standard size 608 bearing hub. The 89a Durometer rating provides a long lasting, rock hard feel. For that reason, 89a is the most popular outdoor durometer rating. The added longevity of a harder wheel gives you not only more speed, but more bang for your buck. The 5-Spoke Hub design makes this a durable and long-lasting wheel Includes 8 wheels, which is enough for a pair of skates