That is a lightweight 17mm aluminum ball-race rollers which can be available to tune your Mini 4WD automobile. These rollers provide less fat and a slight boost in rate, plus superior durability and silky-smooth rotation.
• 17mm Lightweight Aluminum Ball-Race Rollers x2
• Eight holes in each roller alllow for a person weight of 0.81 grams, a saving of approximately 0.25 grams per roller.
• Little parts for accessory are included.
• Built-in 520 ball bearings provide smooth roll.
• Compatible with Mini 4WD and Mini 4WD PRO cars. Some systems may need modification.
