The RCV Performance Pro Series II axles are designed and engineered to handle the most abusive conditions from trail riding to desert racing. With years of experience in racing and working with the top drivers in the industry, RCV has been able to develop the ultimate axle solution. The Pro Series II axles feature RCV's own high-temp SPEC grease, designed to withstand the harshest environments. The outboard Pro Series orange boot is built to precise specifications to be puncture resistant and heat resistant up to 450 degrees. Manufactured in the USA.