Heavy Duty Servo Saver by Hot Racing. FEATURES: CNC 6061-T6 Black aluminum design Optional splines to accommodate many different servos YOU WILL RECEIVE: One servo saver One spline tree with 23S (KO, Sanwa, JR), 24S (Hitec), 25S (Futaba) REQUIREMENTS: Installing on servo SPECIFICATIONS: length: 1-1/2 (38mm) diameter: 1 (25mm)