Fox Shox Fork Volume Spacer. Features: Changing volume spacers internally adjusts the amount of mid stroke and bottom out resistance More spacers = less air volume, providing a more progressive spring curve NA are first generation negative air spring forks using the transfer rod to equalize the air pressure. NA2 is the second generation where the transfer rod is removed. Specs: Model: 36mm Float NA Description: volume spacer, 7.6cc, blue