This is an optional KDE Direct Performance Tail Control Mechanism, and is intended for use with the Align T-Rex 500E PRO and 500E/ESP series helicopters. This tail mechanism replaces the stock Align Tail Rotor Control mechanism for unparalleled precision and authority. The KDE Direct TREX 500 Series Performance Tail Control assembly is the ultimate, slop-free control system available on the market to provide precise tail control and authority. Add the KDE Direct TREX 500 Series Performance Tail Upgrade V2 to the system and you now have a complete, dual-radial ball bearing supported assembly throughout for the ultimate flight characteristics. With the mechanics of the dual-fork supported tail slider, there is no worry of abnormal wear or torque loads on the tail shaft slider for a continuously smooth, failure-free operation even under the hardest and most extreme flying conditions.