You need 8 wheels for a pair of roller skates (2 x 4 packs or 1 x 8 pack). Is the ultimate in indoor skating performance. It is the most advanced and refined performance wheel that Radar has ever made. With over four years of development and countless prototypes tested, the final design is elegant, refined, performance-oriented, and incredibly fun to skate. The original Halo was a landmark wheel design that offered easy access to edging without sacrificing grip and control.The Halo Alloy offers these same performance characteristics coupled with the precision of an aluminum hub for the ultimate response. The Radar Halo Alloy is designed for any indoor skater looking for the highest performance wheel with the best styling. Recommneded Use: Derby, Jam, Dance, Speed. Size: 38 mm x 59 mm. Wheel Colors/Hardness: Yellow 91A, Red 93A, Teal 95A, Fuchsia 97A, Orange 99A.