The PRO4 stabilizer has a new patent pending high fluid speed valve and delivers 3 times the impact damping of the PRO stabilizer and almost double the Elite’s damping. It has a larger shaft and lever with a shear bolt connecting them to handle the added damping forces. Used by team Honda Pro racers; This steering stabilizer is extremely adjustable and rugged. Comes with all hardware needed for an easy installation and mounts up to your TRX in approximately 20 minutes; no drilling, welding, or grinding needed. The Pro4 stabilizer has a built in reservoir to compensate for thermal expansion. The Pro4 stabilizer has adjustments for both straight ahead and turning. CLAMPS- The stock steering stem diameter for the TRX450 is 1.35". Most aftermarket Stems take an A clamp size. Please check your existing stem diameter before ordering to select the correct size clamp. Inquiries for other ATV models or other Precision products please reach us at [email protected].