The X4F framework is made for the CFF suspension system arms being mounted via pivot balls straight to the chassis. The X4F chassis works together with the motor mount and bulkheads using alignment holes the centering pins for each of this mounted elements. Thanks to the centering pins, the construction of structural elements is straighforward, and a lot of significantly the components resist movement in a collision to let you complete the race without losing rate. The narrower design of this framework alongside the perfectly symmetrical form offer optimal flex characteristics. Fits X4F