Ballistic Roller Skate Wheels (set of 8)The Bont roller derby Ballistic is a great mid level wheel that has great grip, roll and wear properties. Ultra lightweight and ultra high performance, for this price, you can't ask for a better wheel. Application: Indoor Size: 60mm Width: 40mm Hardness: 87A The Ballistic roller skate wheel is designed to be used in a rink for indoor skating but it can also be used for outdoor skating. This wheel would make a perfect roller derby fresh meat wheel. It