That is a limited-edition Mini 4WD rushing roller set that commemorates Japan Cup 2020. These lightweight yet tough rollers have integrated 520 ball bearings for smooth motion, and that can be used for both front and back roller setups. The parts have actually an anodized black colored finish with special lettering/logo!
• 19mm Aluminum Ball-Race Rollers x2
• Screws for accessory included.
• suitable for all Mini 4WD and Mini 4WD PRO vehicles. (please be aware that some systems may need modification.