Mini 4WD Pre-Run-In Reverse Rotation Atomic Tuned Motor 2, 25km/h, Set of 6 Made after verifying motor run-in. All 6 motors tested with a Tamiya Speed Checker. When mounted on a machine with 24mm diameter tires, a 3.5:1 super-speed gear ratio, and a weight of 120g, they reach over 25km/h when 3V is applied. These motors are recommended for FM-tuned machines. The brushes are still in good condition, so you can enjoy them for a long time. Run-in Method: These are 6 units that have undergone high-voltage run-in using our shop's Big Boost Oil. No modifications such as advance angle adjustments have been made. These are Tamiya regulation-compliant motors that can be used in official races. Please consider the above.