The Carbon Fiber/Aluminum Fully Adjustable Camera Tray upgrade is well worth the additional cost.  If you will be using a camera over 4lb it is HIGHLY recommended . It offers complete adjustability to allow for many lens combinations while stile allowing the camera center of mass to align with the tilt axis.  It is also at least 4x as rigid as the standard camera tray which means less flexing and wobble of the camera in turbulent wind conditions or rough vehicle motion.

It is a direct bolt on upgrade for 3X Pro v2 and 3X Pro v3 camera mounts.