Optimus® 70mm high performance inline wheels are made of abrasion-resistant, high-density PU roller blade material. ABEC-9 Bearings and Magnetic Cores have been installed, improved precision, speed and durability. Performance-enhancing 82A hardness lead to a smooth & long lasting outdoor skating. Optimus® inline wheels are designed for intermediate players who are looking for wheels with excellent speed, grip and durability. Compatible with rollerblades, inline skates, blades roller skates, scooters, ripstiks, and even some luggage roller suitcase, etc. 70mm wheel diameter, 24mm wheel thickness, 82A hardness; bearing inner diameter 8mm, white plastic spacer inner diameter 6mm. NOTE: the white plastic spacer is suitable for 6mm axle. Please check the specifications in the second product image to ensure it match your skates, and the package doesn't include any axles or screws. These wheels are mainly used for inline roller blades, inline skates, luggage or training wheels. Not recommended to use on uneven ground. Pack of 8 pcs skating wheels, just in line with the needs of one pair of roller shoes, extremely meets your needs.