【 Parts helpful for machine setup 】 These are the tapered type of the 13mm all-aluminum bearing rollers, popular in races. The bowl-shaped (tapered) rollers are designed to help the machine return to the course when it rides up on the course fence. The smooth rotation provided by the embedded 520 bearings is also attractive. In addition to the two bearing rollers, screws and aluminum spacers for installation are also included. 【 Basic Specifications 】 Two 13mm diameter tapered aluminum bearing rollers 【 Usable Machines 】 Mini 4WD PRO, Mini 4WD cars This is the price for a set of 4. #Mini4WD #Rollers #13mm