Radar Energy Crystal Clear Purple Outdoor Quad Roller Skate Wheels by Riedell - Your Choice of Either 62mm or 65mm Wheels - Brand new from Radar Wheels is the newly designed Radar Energy Wheel. Radar Energy Urethane has the most rebound, highest tensil strength, fastest roll of any outdoor wheel to provide an exceptional skating experience. Best outdoor wheel. This new design features a crystal clear theme with a soft 78A Hardness for a smooth roll on any outdoor surface. Radar Energy wheels are the perfect outdoor replacement quad skate wheel for any outdoor skater.