The X4F framework is made for the CFF suspension system hands being mounted via pivot balls directly to the chassis. The X4F framework works together the motor mount and bulkheads making use of alignment holes the centering pins for each of this mounted elements. Thanks to the centering pins, the construction of structural elements is straighforward, and lots of dramatically the components resist movement in a collision to allow you finish the race without losing rate. The narrower design with this framework alongside the completely symmetrical type offer optimal flex characteristics. Fits X4F