Although this roller skate wheel was designed specifically for roller derby, it marks an excellent indoor skate wheel even if you are not playing roller derby. The Evolve indoor roller skate wheel comes in 4 hardness', 88a Blue wheels, 92a purple wheels, 95a red wheels, and black 98a wheels. Indoor floors are typically made of very smooth wood so you can skate on very hard wheels. Softer wheels such as 78a wheels are designed for outdoor skating on surfaces such as concrete and asphalt. To select the best wheel for your indoor skating needs you should consider the grippyness of the floor and your weight. The heavier the skater, the harder the wheel you should select. Similarly, the gripper the floor, the harder the wheel you should select. If you are unsure which hardness is the best for you, select 92a as a good all-around choice. The Bont evolve roller skate replacement wheel is suitable for all brands of roller derby skates including Bont, Riedell, Sure-grip, Antik, Crazy, Impala, and Chaya.