(CF) Carbon Fiber Series - Large Fixed Arm The (CF) - Carbon Fiber Series brings a component based approach to supporting and working with your devices. (CF) Carbon Fiber fixed arm is designed to work with the mounts and bases that have a 20mm ball. This arm is the longest in the series at 280mm (11") and has two end connectors. This is perfect for car mounts, headrest mounts. This is made of solid carbon fiber and not a faux finish. Two other fixed arms are also available in this series. They are the Small 67D-CF-F70X and Medium 67D-CF-F100 Mounts sold seperately.