DESIGNED SPECIFIC FOR DRAG RACING AND OUR BREAKOUT CHASSIS TO KEEP WEIGHT PLANTED TO THE EARTH! 4MM PROVIDES PLENTY OF STIFFNESS TO KEEP THAT SPUR AND PINION TOGETHER NO MATTER THE KV OR TURN OF YOUR MOTOR. OUR 61046 CAN BE USED IN ANY ASSOCIATED PLATFORM BUT NOTE THAT YOU MAY NEED A TRANSMISSION RISER IN SOME APPLICATIONS.