【 Race Ready Chassis 】 This is an assembly kit model of the high-performance Mini 4WD racer of the Knuckle-Breaker Black Special. The semi-monocoque Super X chassis features its superb strength, and motor attachment/detachment is possible with the body mounted onto the chassis. The cross type battery holder ensures secure attachment of the batteries. Kit comes with 24mm diameter slick tires and has a choice from 3.5:1 and 4:1 gear ratios. The vertical fins on both sides provide excellent stability on straight sections. No cement is required for assembly, and a wide range of Grade-Up Parts is available to customize your machine.