Bankroll x4 quad roller skate wheels are made for rough roads and outdoor roller skating. These wheels feature a 78A hardness and 62mm height. They are durable, reliable, and will outlast most other outdoor roller skate wheels. Compounded by some of the best in the business, these wheels are soft enough to go over cracks in sidewalks, small pebbles, and harsh surfaces and prevent a rough ride. These wheels can be used indoors, too. When used indoors they will feel a little slow and mushy, but smooth surfaces will not hurt the wheels or skates. Most skaters like the x4 wheel because it is easy to clean and resists collecting road dirt and grime. These wheels can be used on any modern skate with an 8mm axle and can be fitted with most modern skate bearings that are 8mm. Please be sure to select the correct choice of wheels needed - 4pk without Bearings / 4pk With Bearings / 8pk without Bearings / 8pk with Bearings.