***This is a pack of 4 wheels*** Radar Wheels feature MDI Urethane Technology for increased resilience (resistance), better grip (control), with more durability (longer lasting). Faster, Smoother, and a Quieter Roll; Radar Wheels are designed for performance skating. Recommended Use: Indoor (Art Skaters). MDI Urethane Technology. Without Hub. Extended Roll for all skating surfaces. Extra Grip on all coated floors. These are sold in packs of 4.